WP:CITE

Citations, frequently called references, are an important part of any Wikipedia article, serving to identify the reliable sources on which the information in the article is based. In most cases, citations for specific pieces of information contained in an article are given in the form of footnotes, though they can also appear within the body of an article.

Wikipedia's Verifiability policy describes when sources should be cited, and what kind of sources are considered reliable. It requires inline citations for any material challenged or likely to be challenged, and for all quotations, anywhere in article space. However, editors are strongly advised to provide citations for all information added to Wikipedia; any detail risks being unexpectedly challenged or even eventually removed.

This page contains information on how to place and format citations. Each article should use the same citation method throughout. If an article already has citations, adopt the method in use or seek consensus on the talk page before changing it. While you should try to write citations correctly, what matters most is that you provide enough information to identify the source. Others will improve the formatting if needed.

Types of citation
A full citation fully identifies a reliable source and, where applicable, the place in that source (such as a page number) where the information in question can be found. For example: Rawls, John. A Theory of Justice. Harvard University Press, 1971, p. 1. This type of citation is usually given as a footnote, and is the most commonly used citation method in Wikipedia articles.

An inline citation means any citation added close to the material it supports, for example after the sentence or paragraph, normally in the form of a footnote.

A general reference is a citation to a reliable source that supports content, but is not displayed as an inline citation. General references are usually listed at the end of the article in a References section. They may be found in underdeveloped articles, especially when all article content is supported by a single source. They may also be listed by author alphabetically in a References section in more developed articles as a supplement to inline citations.

A short citation is an inline citation that identifies the place in a source where specific information can be found, but without giving full details of the source – these will have been provided in a general reference. For example: Rawls 1971, p. 1. This system is used in some articles; the short citations may be given either as footnotes, or as parenthetical references within the text.

In-text attribution means saying within the article text itself (not as a mere footnote) where particular statements come from. This is done especially with statements of opinion, uncertain facts, and quotations. Usually the in-text attribution does not specify full details of the source text – this is done with a footnote in the normal way. For example: According to John Rawls,[5]... See In-text attribution below.

When and why to cite sources
By citing sources for Wikipedia content, you enable other editors and readers to verify that the information given is supported by reliable sources, thus improving the credibility of Wikipedia and showing that the material is not original research. You also help readers find additional information on the subject; and you avoid committing plagiarism (by giving credit to the source of your words or ideas).

In particular, sources are required for material that is challenged or likely to be challenged – if reliable sources cannot be found for challenged material, it is likely to be removed from the article. Sources are also required when quoting someone, with or without quotation marks, or closely paraphasing a source. However, the citing of sources is not limited to those situations – editors are always encouraged to add or improve citations for any information contained in an article.

Citations are especially desirable for statements about living persons, particularly when the statements are contentious or potentially defamatory. In accordance with the biography of living persons policy, unsourced information of this type is likely to be removed on sight.

Citations are not used on disambiguation pages (sourcing for the information given there should be done in the target articles). Citations are also often discouraged in the lead section of an article, insofar as it summarizes information for which sources are given later in the article, although such things as quotations and particularly controversial statements should be supported by citations even in the lead.

For an image or other media file, details of its origin and copyright status should appear on its file page. Image captions should be referenced as appropriate just like any other part of the article. A citation is not needed for descriptions such as alt text that are verifiable directly from the image itself, of for text that merely identifies a source (e.g., the caption "Belshazzar's Feast (1635)" for File:Rembrandt-Belsazar.jpg).

Inline citations
Inline citations allow the reader to associate a given bit of material in an article with the specific reliable source(s) that support the material. Inline citations are most commonly added using either footnotes (long or short) or parenthetical references. This section describes how to add either type, and also describes how to create a list of full bibliography citations to support shortened footnotes or parenthetical references.

How to place an inline citation using ref tags
To create a footnote, use the  syntax at the appropriate place in the article text, for example:


 * tag or the reflist template. For example:





The footnotes will then automatically be listed under that section heading. Each numbered footnote marker in the text is a clickable link to the corresponding footnote, and each footnote contains a caret which links back to the corresponding point in the text. Scrolling lists, or lists of citations appearing within a scroll box, should never be used. This is because of issues with readability, browser compatibility, accessibility, printing, and site mirroring.

If an article contains a list of general references, this is placed in a separate section, titled (for example) "References". This usually comes immediately after the section(s) listing footnotes, if any. (If the general references section is called "References", then the citations section is usually called "Notes".)

Separating citations from explanatory footnotes
If an article contains both footnoted citations and other (explanatory) footnotes, then it is possible (but not necessary) to divide them into two separate lists, using the grouping feature described in the Grouping footnotes section of the footnotes help page. The explanatory footnotes and the citations are then placed in separate sections, called (for example) "Notes" and "References" respectively.

Repeated citations
For multiple use of the same citation or footnote, you can also use the named references feature, choosing a name to identify the citation, and typing  . Thereafter, the same footnote may be reused any number of times by typing just  . For more details of this syntax, see Multiple references to the same footnote on the footnotes help page.

Avoiding clutter
Inline references can significantly bloat the wikitext in the edit window and can be extremely difficult and confusing. There are three methods that avoid clutter in the edit window: list-defined references, short citations or parenthetical references. (As with other citation formats, articles should not undergo large scale conversion between formats without consensus to do so.)

Citing multiple pages of the same source
When an article cites many different pages from the same source, most Wikipedia editors use short citations in footnotes. Other methods include short citations in parenthesis and the template rp.

The use of ibid., Id. (or similar abbreviations) is discouraged, as these may become broken as new references are added (op. cit. is less problematic in that it should refer explicitly to a citation contained in the article; however, not all readers are familiar with the meaning of the terms). If the use of ibid is extensive, use the ibid template.

Short citations
Some Wikipedia articles use short citations, giving summary information about the source together with a page number, as in. These are used together with general references, which give full details of the sources, but without page numbers, and are listed in a separate "References" section. Short citations are used in articles which apply parenthetical referencing (see below), but they can also be used as footnote citations, as described here.

Forms of short citations used include author-date referencing (APA style, Harvard style, or Chicago style), and author-title or author-page referencing (MLA style or Chicago style). As before, the list of footnotes is automatically generated in a "Notes" or "Footnotes" section, which immediately precedes the "References" section containing the general references. Short citations can be written manually, or by using the  or   templates. (Note that templates should not be added without consensus to an article that already uses a consistent referencing style.) The short citations and general references may be linked so that the reader can click on the short note to find full information about the source. See the template documentation for details and solutions to common problems. For variations with and without templates, see wikilinks to full references. For a set of realistic examples, see these.

This is how short citations look in the edit box:





The Sun is pretty big, &lt;ref> Miller 2005, p. 23.&lt;/ref> but the Moon is not so big. &lt;ref> Brown 2006, p. 46.&lt;/ref> The Sun is also quite hot. &lt;ref> Miller 2005, p. 34.&lt;/ref>

&#61;= Notes ==

 

&#61;= References ==

* '''Brown, Rebecca (2006). "Size of the Moon," Scientific American, 51(78)'''.

* '''Miller, Edward (2005). The Sun. Academic Press'''.



This is how they look in the article:



The Sun is pretty big,[1] but the Moon is not so big.[2] The Sun is also quite hot.[3]

Notes

^ Miller 2005, p. 23.

^ Brown 2006, p. 46.

^ Miller 2005, p. 34.</li>

</ol>

References


 * Brown, Rebecca (2006). "Size of the Moon", Scientific American, 51(78).


 * Miller, Edward (2005). The Sun. Academic Press.

Shortened notes using titles rather than publication dates would look like this in the article:

<blockquote style="background:white; padding:1em; border:1px solid #999;">

Notes

<li id="noteFoot01b"

>^ Miller, The Sun, p. 23.</li>

<li id="noteFoot02b"

>^ Brown, "Size of the Moon", p. 46.</li>

<li id="noteFoot03b"

>^ Miller, The Sun, p. 34.</li>

</ol>

Since the links are placed manually it is easy to introduce errors such as duplicate anchors and unused references. The script User:Ucucha/HarvErrors will show many related errors. Duplicate anchors may be found by using the W3C Markup Validation Service.

Parenthetical referencing
While most articles use footnote citations as described in the above sections, some articles use a parenthetical referencing style. Here, short citations in parentheses, such as (Smith 2010, p. 1), are placed within the article text itself. Full details of each source used are given in a general reference, e.g. Smith, John. Name of Book. Cambridge University Press, 2010. The general references are listed in alphabetical order, according to the authors' surnames, at the end of the article in a "References" section.

Several forms of short citation are used in Wikipedia; see Short citations above. The inline citation and general reference may be linked using a template (see linking inline and full citations); as with other citation templates, these should not be added to articles without consensus.

This is how it looks in the edit box:

<blockquote style="color:#999; background:#F4F0EC; padding:1em; border:1px solid DarkSeaGreen;">



The Sun is pretty big (Miller 2005, p. 1), but the Moon is not so big (Brown 2006, p. 2). The Sun is also quite hot (Miller 2005, p. 3).

&#61;= References ==

* '''Brown, R (2006). "Size of the Moon", Scientific American, 51(78)'''.

* '''Miller, E (2005). The Sun, Academic Press'''.

</tt>

This is how it looks in the article:

<blockquote style="background:white; padding:1em; border:1px solid #999;">

The Sun is pretty big (Miller 2005, p. 1), but the Moon is not so big (Brown 2006, p. 2). The Sun is also quite hot (Miller 2005, p. 3).

References


 * Brown, R (2006). "Size of the Moon", Scientific American, 51(78).


 * Miller, E (2005). The Sun, Academic Press.

Notice that, unlike footnotes, parenthetical references are placed before adjacent punctuation such as commas and full stops.

General references
A general reference is a citation to a reliable source that supports content, but is not displayed as an inline citation. General references are usually listed at the end of the article in a "References" section, and are usually sorted on the last name of the author or the editor.

Examples of general reference sections are given above, in the sections on short citations and parenthetical references.

In addition to their use when short or parenthetical references are used, a general references section may also be included in an article that uses full inline citations, particularly if such citations have not yet been given for all the information in the article. In underdeveloped articles, a general references section may exist even though no inline citations at all have yet been added, especially when all article content is supported by a single source. The disadvantage of using general references alone is that text-source integrity is lost, unless the article is very short.

What information to include
Listed below is the information which a typical inline citation or general reference will provide, in order to identify the source, assist readers in finding it, and (in the case of inline citations) indicate the place in the source where the information is to be found. (If an article uses parenthetical referencing or short citations, then the inline citations will refer to this information in abbreviated form, as described in the relevant sections above.)

Books
Citations for books typically include the name of the author(s), the title of the book (in italics), the volume if applicable, the city of publication (optional), the name of the publisher, the year of publication, and the ISBN number (written using the syntax described at WP:ISBN) where available.

Inline citations should additionally give the relevant page number or range of page numbers. Chapter numbers can also be given if appropriate. When specifying a page number, it is helpful to specify the date and edition used, as pagination can change between editions. If the source is an e-book that does not provide page numbers, the citation should include information that enables readers to locate the source material within the e-book, such as chapter number, paragraph number, or a short quote from the source itself.

Citations for individually authored chapters in books typically include the name of the author, the title of the chapter, the name of the book's editor,    and other information described above (book name, ISBN, etc). Do not present the information in a way that implies that the editor is the author.

When a book is available online through a site such as Internet Archive, Project Gutenberg, or Google Books, it may be useful to provide link to the book so readers can view the source. Use the external link syntax, so that clicking on the book title will take the reader to the book. If a specific page in the book is referenced, it may be specified in the link, for example



A link to a specific page in a Google Books should only be added if the book is available for preview; such links will not work if the book is only available in snippet view. Like other variations on citation styles, there is no requirement either to add or remove such links.

Journal articles
Citations for journal articles typically include the name of the author(s), the year and sometimes month of publication, the title of the article (within quotation marks), the name of the journal (in italics), the volume number, issue number and page numbers (article numbers in some electronic journals). It is also helpful to provide DOI, PMID and/or other identifiers where available.

Inline citations usually also include specific page numbers, as described above for books.

If the article is available online, use external link syntax to link the article title to the relevant Web page, for example:

Newspaper articles
Citations for newspaper articles typically include the name of the newspaper (in italics), the date of publication, the byline (author's name) if any, the title of the article (within quotation marks), and the city of publication if not included in the name of the newspaper. Page number(s) are optional.

If the article is available online, link the article's title to the relevant Web address, as described above for journal articles.

Web pages
Citations for World Wide Web pages typically include the name of the author(s), the title of the article (within quotation marks), the name of the website, the date of publication (if known), the date you retrieved the page, for example Retrieved 2008-07-15. (this is required if the publication date is unknown). Page number(s) can be added if applicable.

Recordings
Citations for sound recordings typically include the name of the composer(s)/script writer(s), name of the performer(s), title of the song or individual track (in quotation marks), title of the album in italics (if applicable), name of the record label, year of release, medium (for example: LP, audio cassette, CD, MP3 file).

Citations for films, TV episodes, or video recordings typically include the name of the director (and the producer if relevant), names of major performers, the title of the episode in quotation marks (if applicable), the title of the film or TV series (in italics), the name of the studio, the year of release, the medium (for example: film, videocassette, DVD).

Where applicable, an inline citation should also give the approximate time in the recording at which the event or point of interest occurs. When doing this, be as precise as possible about the version of the source that you are citing; for example, movies are often released in different editions or "cuts", and timings may differ between them.

Say where you read it
Don't cite a source unless you've seen it for yourself. Where you want to cite John Smith, but you've only read Paul Jones who cites Smith, write it like this (this formatting is just an example):

"Smith, John. Name of Book I Haven't Seen, Cambridge University Press, 2009, p. 1, cited in Paul Jones (ed.). Name of Encyclopedia I Have Seen. Oxford University Press, 2010, p. 2."

However, if you have read Smith's book yourself, you may cite it directly; there is no need to give credit to any sources, search engines, websites, library catalogs, etc., that led you to that book.

Additional annotation
In most cases it is sufficient for a citation footnote simply to identify the source (as described in the sections above); readers can then consult the source to see how it supports the information in the article. Sometimes, however, it is useful to include additional annotation in the footnote, for example to indicate precisely which information the source is supporting (particularly when a single footnote lists more than one source – see Bundling citations and Text-source integrity below). A footnote may also contain a relevant exact quotation from the source, if this may be of interest (this is particularly useful if the source is not easily accessible).

In the case of non-English sources, it may be helpful to quote from the original text and then give an English translation. If the article itself contains a translation of a quote from such a source (without the original), then the original should be included in the footnote. See Non-English sources in the verifiability policy for more information.

Citation style
While citations should aim to provide the information listed above, there is no one single style for doing this, in terms of ordering of the information, punctuation, etc. A consistent style should be used within any given article, but it is not necessary to maintain consistency between articles – for how to deal with variation, see the following section.

A number of citation styles exist (some relevant Wikipedia articles include Citation, APA style, MLA style, The Chicago Manual of Style, Author-date referencing, Vancouver system and Bluebook). Examples can be found at Citing sources/Example style.

Although nearly any consistent style may be used, avoid all-numeric date formats other than YYYY-MM-DD, because of the ambiguity concerning which number is the month and which the day. For example, 2002-06-11 may be used, but not 11/06/2002. The YYYY-MM-DD format should in any case be limited to Gregorian calendar dates where the year is after 1582.

Variation in citation methods
As described in various sections of this page, different articles use different citation systems, styles and methods. Points of difference include:


 * whether an article uses full citations, short citations in footnotes, or parenthetical referencing;


 * what the citation/reference sections of the article are called, and whether explanatory footnotes are grouped separately from citation footnotes;


 * the styling of the citations themselves;


 * whether citations are produced using citation templates;


 * whether list-defined references are used.

On all of these points, Wikipedia does not have a single house style. Editors may choose any option they want; one article need not match what is done in other articles. However, citations within a given article should follow a consistent style.

It is therefore considered helpful:


 * when adding citations, to try to follow the system and style already in use in the article (if any);


 * to improve existing citations by adding missing information (for example, replacing bare URLs with full bibliographic citations);


 * to replace (or supplement) some or all general references with inline citations;


 * to change existing citations to make them follow a consistent system and style, if there is currently inconsistency within the article. If there is disagreement about which style is best, defer to the style used by the first major contributor;


 * if you think another system or style would be more appropriate for the article than what is already in use, to propose the change on the talk page, and wait for consensus to emerge.

Editors should not attempt to change an article's established citation style merely on the grounds of personal preference, or without first seeking consensus for the change.

Handling links in citations
As noted above under What information to include, it is helpful to include hyperlinks to source material, when available. Here we note some issues concerning these links.

Avoid embedded links
Embedded links to external websites should not be used as a form of inline citation, because they are highly susceptible to linkrot. Wikipedia allowed this in its early years—for example by adding a link after a sentence, like this, which looks like this. This is no longer recommended. Raw links are not recommended in lieu of properly written out citations, even if placed between ref tags, like this.

Embedded links should never be used to place external links in the body of an article, like this: "Apple, Inc. announced their latest product..."

Convenience links
A convenience link is a link to a copy of your source on a webpage provided by someone other than the original publisher or author. For example, a copy of a newspaper article no longer available on the newspaper's website may be hosted elsewhere. When offering convenience links, it is important to be reasonably certain that the convenience copy is a true copy of the original, without any changes or inappropriate commentary, and that it does not infringe the original publisher's copyright. Accuracy can be assumed when the hosting website appears reliable. Where several sites host a copy of the material, the site selected as the convenience link should be the one whose general content appears most in line with Neutral point of view and Verifiability.

Indicating availability
If your source is not available online, it should be available in reputable libraries, archives, or collections. If a citation without an external link is challenged as unavailable, any of the following is sufficient to show the material to be reasonably available (though not necessarily reliable): providing an ISBN or OCLC number; linking to an established Wikipedia article about the source (the work, its author, or its publisher); or directly quoting the material on the talk page, briefly and in context.

Links to sources
For a source available in hardcopy, microform, and/or online, omit, in most cases, which one you read. While it is useful to cite author, title, edition (1st, 2d, etc.), and similar information, it generally is not important to cite a database such as ProQuest, EbscoHost, or JStor (see the list of academic databases and search engines) or to link to such a database requiring a subscription or a third party's login. The basic bibliographic information you provide should be enough to search for the source in any of these databases that have the source. Don't add a URL that has a part of a password embedded in the URL. However, you may provide the DOI, ISBN, or another uniform identifier, if available. If the publisher offers a link to the source or its abstract that does not require a payment or a third party's login for access, you may provide the URL for that link. And if the source only exists online, give the link even if access is restricted.

Preventing and repairing dead links
To help prevent dead links, persistent identifiers are available for some sources. Some journal articles have a digital object identifier (DOI); some online newspapers and blogs, and also Wikipedia, have permalinks that are stable. When permanent links aren't available, consider archiving the referenced document when writing the article; on-demand web archiving services such as WebCite (http://www.webcitation.org) are fairly easy to use (see pre-emptive archiving).

Dead links should be repaired or replaced if possible. Do not delete a citation merely because the URL is not working today. Follow these steps when you encounter a dead URL being used as a reliable source to support article content:


 * 1) Confirm status: First, check the link to confirm that it is dead and not temporarily down. Search the website to see whether it has been rearranged.


 * 1) Check for web archives: Several archive services exist; add one of these URLs if available:


 * 1) * The Internet Archive and WebCite have billions of archived webpages. See Using the Wayback Machine and Using WebCite.


 * 1) * The UK Government Web Archive (http://www.nationalarchives.gov.uk/webarchive/) preserves 1500 UK central government websites. Note: Most archives currently operate with a delay of ~18 months before a link is made public. As a result, editors should wait ~24 months after the link is first tagged as dead before declaring that no web archive exists. Dead URLs to reliable sources should normally be tagged with, so that you can estimate how long the link has been dead.


 * 1) Remove convenience links: If the material was published on paper (e.g., academic journal, newspaper article, magazine, book), then the URL is not necessary. Simply remove it.


 * 1) Find a replacement source: Search the web for quoted text or the article title. Consider contacting the website/person that originally published the reference and asking them to republish it. Ask other editors for help finding the reference somewhere else. Find a different source that says essentially the same thing as the reference in question.


 * 1) Remove hopelessly lost web-only sources: If the source material does not exist offline, and if there is no archived version of the webpage (be sure to wait ~24 months), and if you are unable to find another copy of the material, then the dead citation should be removed and the material it supports should be regarded as unverifiable. If it is material that is specifically required by policy to have an inline citation, then please consider tagging it with . It may be helpful to future editors if you move the citation to the talk page with an explanation.

Text-source integrity
When using inline citations, it is important to maintain text-source integrity. The point of an inline citation is to allow readers and other editors to check that the material is sourced; that point is lost if the citation is not clearly placed. The distance between material and its source is a matter of editorial judgment, but adding text without placing its source clearly can lead to allegations of original research, violations of the sourcing policy, and even plagiarism. Editors should exercise caution when rearranging or inserting material to ensure that text-source relationships are maintained.

When new text is inserted into a paragraph make sure that it is clear what facts the inline citations support. For example

<blockquote style="background:white; padding:1em; border:1px solid #999;">

The sun is pretty big.<sup id="nbFoot01a" class="reference">[1] The sun is also quite hot.<sup id="nbFoot03a" class="reference">[2]

Notes

<li id="noteFoot01a"

>^ Miller, Edward. The Sun. Academic Press, 2005, p. 1.</li>

<li id="noteFoot03a"

>^ Smith, John. The Sun's Heat. Academic Press, 2005, p. 2.</li>

</ol>

Do not add facts into a fully cited paragraph or sentence

<blockquote style="background:white; padding:1em; border:1px solid #999;">

The sun is pretty big, but the moon is not so big.<sup id="nbFoot01a" class="reference">[1] The sun is also quite hot.<sup id="nbFoot03a" class="reference">[3]

Notes

<li id="noteFoot01a"

>^ Miller, Edward. The Sun. Academic Press, 2005, p. 1.</li>

<li id="noteFoot03a"

>^ Smith, John. The Sun's Heat. Academic Press, 2005, p. 2.</li>

</ol>

without including a source to cover the new information.

<blockquote style="background:white; padding:1em; border:1px solid #999;">✅

The sun is pretty big,<sup id="nbFoot01a" class="reference">[1] but the moon is not so big.<sup id="nbFoot02a" class="reference">[2] The sun is also quite hot.<sup id="nbFoot03a" class="reference">[3]

Notes

<li id="noteFoot01a"

>^ Miller, Edward. The Sun. Academic Press, 2005, p. 1.</li>

<li id="noteFoot02a"

>^ Brown, Rebecca. "Size of the Moon," Scientific American, 51(78):46.</li>

<li id="noteFoot03a"

>^ Smith, John. The Sun's Heat. Academic Press, 2005, p. 2.</li>

</ol>

Including too many citations within a sentence my be aesthetically unpleasant:

<blockquote style="border:1px solid #999;">

The sun is the closest star to the planet Earth, but the moon is even closer.

So consider placing them at a more aesthetically pleasant location:

<blockquote style="border:1px solid #999;">

The sun is the closest star to the planet Earth, but the moon is even closer.

or

<blockquote style="border:1px solid #999;">

The sun is the closest star to the planet Earth, but the moon is even closer.

However this solution brings its own problems:


 * A string of independent citations can also appear aesthetically unpleasant so consider bundling them into one.


 * Identifying which inline citation supports which fact can be more difficult unless additional information is added to the inline citations to explicitly identify what portion of the sentence they cover.


 * Maintenance becomes more difficult. When adding more information to the sentence from yet another source it may be difficult to work out precisely where to place the new citation. If the text is rearranged during a copy edited greater care needs to be taken with rearranging the citations, particularly as the inline citations will be renumbered during their repositioning.

For example if the sentence

<blockquote style="border:1px solid #999;">

The sun is the closest star to the planet Earth, but the moon is even closer.

is rearranged like this:

<blockquote style="border:1px solid #999;">

The moon is closer to planet Earth than the nearest star which is called the sun.

It will be fairly easy to check that the citations support the information in the rearranged sentence. This rearrangement is more difficult to check:

<blockquote style="border:1px solid #999;">

The sun is the closest star to the planet Earth, but the moon is even closer.

<blockquote style="border:1px solid #999;">

The moon is closer to planet Earth than the nearest star which is called the sun.

Bundling citations
Sometimes the article is more readable if multiple citations are bundled into a single footnote. For example, when there are multiple sources for a given sentence, and each source applies to the entire sentence, the sources can be placed at the end of the sentence, like this. Or they can be bundled into one footnote at the end of the sentence or paragraph, like this.

Bundling is useful if the sources each support a different portion of the preceding text, or if the sources all support the same text. Bundling has several advantages:


 * It helps readers and other editors see at a glance which source supports which point, maintaining text-source integrity;


 * It avoids the visual clutter of multiple clickable footnotes inside a sentence or paragraph;


 * It avoids the confusion of having multiple sources listed separately after sentences, with no indication of which source to check for each part of the text, such as this.


 * It makes it less likely that inline citations will be moved inadvertently when text is re-arranged, because the footnote states clearly which source supports which point.

When formatting multiple citations in a footnote, there are several layouts available, as illustrated below. Within a given article, only a single layout should be used.

<blockquote style="background:white; padding:1em; border:1px solid #999;">

The sun is pretty big, but the moon is not so big. The sun is also quite hot.<sup id="nbFoot01a" class="reference">[1]

Notes

Bullets

<li id="noteFoot01a" value="1">

^ For the sun's size, see Miller, Edward. The Sun. Academic Press, 2005, p. 1.


 * For the moon's size, see Brown, Rebecca. "Size of the Moon," Scientific American, 51(78):46.


 * For the sun's heat, see Smith, John. The Sun's Heat. Academic Press, 2005, p. 2.</li>

Line breaks

<li id="noteFoot02a" value="1">

^ For the sun's size, see Miller, Edward. The Sun. Academic Press, 2005, p. 1.

For the moon's size, see Brown, Rebecca. "Size of the Moon," Scientific American, 51(78):46.

For the sun's heat, see Smith, John. The Sun's Heat. Academic Press, 2005, p. 2.</li>

Paragraph

<li id="noteFoot03a" value="1">

^ For the sun's size, see Miller, Edward. The Sun. Academic Press, 2005, p. 1. For the moon's size, see Brown, Rebecca. "Size of the Moon," Scientific American, 51(78):46. For the sun's heat, see Smith, John. The Sun's Heat. Academic Press, 2005, p. 2.</li>

</ol>

In-text attribution
In-text attribution is the attribution inside a sentence of material to its source, in addition to an inline citation after the sentence. In-text attribution should be used with direct speech (a source's words between quotation marks); indirect speech (a source's words without quotation marks); and close paraphrasing. It can also be used when loosely summarizing a source's position in your own words. It avoids inadvertent plagiarism, and helps the reader see where a position is coming from. An inline citation should follow the attribution, usually at the end of the sentence or paragraph in question.

For example:

When using in-text attribution, make sure it doesn't lead to an inadvertent neutrality violation. For example, the following implies parity between the sources, without making clear that the position of Dawkins is the majority view:

Neutrality issues apart, there are other ways in-text attribution can mislead. The sentence below suggests The New York Times has alone made this important discovery:

Simple facts such as this can have inline citations to reliable sources as an aid to the reader, but normally the text itself is best left as a plain statement without in-text attribution:

Dealing with unsourced material
If an article is unreferenced, you can tag it with the unreferenced template, so long as it is not nonsensical or a biography of a living person, in which case request admin assistance.


 * If a claim is doubtful but not harmful, use the citation needed template, which will add an inline tag, but remember to go back and remove the claim if no source is produced within a reasonable time.


 * If a claim is doubtful and harmful, remove it from the article. You may want to move it to the talk page and ask for a source, unless it is very harmful or absurd, in which case it should not be posted to the talk page either. Use your common sense.


 * All unsourced and poorly sourced contentious material about living persons must be removed from articles and talk pages immediately. See Biographies of living persons and Libel.

Citation templates and tools

 * For a comparison of citations using templates with citations written freehand, see Wikipedia:Citing sources/Example edits for different methods.

Citation templates can be used to format citations in a consistent way. The use of citation templates is neither encouraged nor discouraged: an article should not be switched between templated and non-templated citations without good reason and consensus – see Variation in citation methods above.

Metadata
Citations may be accompanied by metadata, though it is not mandatory. Most citation templates on Wikipedia use the COinS standard. Metadata such as this allow browser plugins and other automated software to make citation data accessible to the user, for instance by providing links to their library's online copies of the cited works. In articles that format citations manually, metadata may be added manually in a span, according to the COinS specification; or the templates Template:Citation metadata or Template:COinS can be used.

Citation processing tools

 * =16393670&citelang=en&template=monobook Citation template generator] - generates completed templates using identifying numbers such PMIDs (PubMed IDs).


 * Template:Citation/core – a core template used by other citation templates


 * User:Citation bot (formerly DOI bot) – a bot that automatically fixes common errors in individual citations, and adds missing fields


 * User:CitationTool – a tool for finding article-level citation errors and fixing them. Not currently functional.


 * Reflinks adds titles to bare references and other cleanup

Programming tools

 * Wikicite is a free program that helps editors to create citations for their Wikipedia contributions using citation templates. It is written in Visual Basic .NET, making it suitable only for users with the .NET Framework installed on Windows, or, for other platforms, the Mono alternative framework. Wikicite and its source code is freely available; see the developer's page for further details.


 * Wikicite+ is a program based on the original Wikicite source code. It features extra validation, bug fixes, additional cite templates (such as cite episode) as well as tools for stub sorting and more. It is also available for free under the Apache License 2.0 and is open source.


 * User:Richiez has tools to automatically handle citations for a whole article at a time. Converts occurrences of or  to properly formatted footnote or Harvard-style references. Written in ruby and requires a working installation with basic libraries.


 * pubmed2wiki.xsl an XSL stylesheet transforming the XML output of PubMed to Wikipedia refs.


 * RefTag by Apoc2400 creates a prefilled cite book template with various options from a Google Books URL. The page provides a bookmarklet for single-click transfer.


 * wikiciter web interface, does google books, pdf files, beta.

Citation export tools
You can insert a link beside each citation in Wikipedia, allowing you to export the citation to a reference manager such as EndNote. To install the script just add the following line to Special:MyPage/skin.js (applies to the currently selected skin) or Special:MyPage/common.js (applies to all skins)"

Then save the page and follow the instructions at the top of that page to bypass your browser's cache.