enWikipedia:Citing sources
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WP:REF redirects here; you may also be looking for details on the <ref> element or the Wikipedia Reference Desk or Wikipedia:Citation templates.
"WP:CITE" redirects here. For information on citing Wikipedia articles, see WP:CITING.
This page is a style guide, describing how to write citations in articles. Wikipedia:Verifiability, which is policy, says that attribution is required for "direct quotes and for material that is challenged or likely to be challenged." Any material that is challenged, and for which no source is provided within a reasonable time (or immediately if it's about a living person), may be removed by any editor. For information about the importance of using good sources in biographies of living persons, see Wikipedia:Biographies of living persons, which is also policy. If you don't know how to format a citation, provide as much information as you can, and others will help to write it correctly. Why sources should be citedWikipedia is by its very nature a work by people with widely different knowledge and skills. The reader needs to be assured that the material within it is reliable: this is especially important where statements are made about controversial issues or living persons. The purpose of citing your sources is:
Use of termsThis guideline uses the terms "source," "reference," and "citation" interchangeably. When to cite sourcesWhen adding material that is challenged or likely to be challengedWP:V says: All material that is challenged or likely to be challenged needs a reliable, published source. The need for citations is especially important when writing about opinions held on a particular issue. Avoid weasel words where possible, such as, "Some people say ..." Instead, make your writing verifiable: find a specific person or group who holds that opinion and give a citation to a reputable publication in which they express that opinion. Remember that Wikipedia is not a place for expressing your own opinions or for original research. Because this is the English Wikipedia, English-language sources should be given whenever possible, and should always be used in preference to other language sources of equal caliber. However, do give references in other languages where appropriate. If quoting from a different language source, an English translation should be given with the original-language quote beside it. When quoting someoneYou should always add a citation when quoting published material, and the citation should be placed directly after (or just before) the quotation, which should be enclosed within double quotation marks — "like this" — or single quotation marks if it is a quote-within-a-quote — "and here is such a 'quotation' as an example." For long quotes, you may wish to use Quotation templates. When adding material to the biography of a living personBiographies of living persons should be sourced with particular care, for legal and ethical reasons. All contentious material about living persons must cite a reliable source. If you find unsourced or poorly sourced contentious material about a living person — whether in an article or on a talk page — remove it immediately! Do not leave it in the article while you request a source. Do not move it to the talk page. This applies whether the material is in a biography or any other article. When checking content added by othersYou can also add sources for material you did not write. Adding citations is an excellent way to contribute to Wikipedia. See Wikipedia:WikiProject Fact and Reference Check for organized efforts to add citations. When uploading an image
Images must include source details and a copyright tag on the image description page. It is important that you list the author of the image if known (especially if different from the source), which is important both for copyright and for informational purposes. Some copyright licenses require that the original author receive credit for their work. If you download an image from the web, you should give the URL:
If you got the image from an offline source, you should specify:
Any image with a nonfree copyright license must be accompanied by a non-free use rationale (also called a fair use rationale) for each article in which the image is used. How to cite sources
Citation styles
There are a number of citation styles and systems used in different fields, all including the same information, with different punctuation use, and with the order of appearance varying for the author's name, publication date, title, and page numbers. Any style or system is acceptable on Wikipedia so long as articles are internally consistent. You should follow the style already established in an article, if it has one; where there is disagreement, the style or system used by the first editor to use one should be respected. General references versus inline citationsArticles can be supported with references in two ways: the provision of general references – books or other sources that support a significant amount of the material in the article – and inline citations, which are mandated by the featured article criteria and (to a lesser extent) the good article criteria. Inline citations are references within the text that provide source information for specific statements. They are appropriate for supporting statements of fact and are needed for statements that are challenged or likely to be challenged, including contentious material about living persons, and for all quotations. Say where you found the material
It is improper to copy a citation from an intermediate source without making clear that you saw only that intermediate source. For example, you might find some information on a Web page which says it comes from a certain book. Unless you look at the book yourself to check that the information is there, your reference is really the Web page, which is what you must cite. The credibility of your article rests on the credibility of the Web page, as well as the book, and your article must make that clear.
Provide full citationsAll citation techniques require detailed full citations to be provided for each source used. Full citations must contain enough information for other editors to identify the specific published work you used. Full citations for books typically include: the name of the author, the title of the book or article, the date of publication, and page numbers. The name of the publisher, city of publication, and ISBN are optional. For journal articles, include volume number, issue number and page numbers. Citations for newspaper articles typically include the title of the article in quotes, the byline (author's name), the name of the newspaper in italics, date of publication, page number(s), and the date you retrieved it if it is online. Provide page numbersWhen citing books and articles, provide page numbers where appropriate. Page numbers should be included whenever possible in a citation that accompanies a specific quotation from, or a paraphrase or reference to, a specific passage of a book or article. The edition of the book should be included in the reference section, or included in the footnote, because pagination can change between editions. Page numbers are especially important in case of lengthy unindexed books. Page numbers are not required when a citation accompanies a general description of a book or article, or when a book or article, as a whole, is being used to exemplify a particular point of view. Inline citation stylesHarvard referencing
According to The Oxford Style Manual, the Harvard system is the most commonly used reference method in the physical and social sciences (Ritter 2002). Under the Harvard referencing system, a reference source such as a book is cited in the text in parentheses, after the section, sentence, or paragraph for which the book was used as a source, using the surname of the author and the year of publication only, with the parentheses closing before the period, as in (Jones 2005). Page numbers must be included in a citation that accompanies a specific quotation from, or a paraphrase or reference to, a specific passage of a book or article. They usually follow the date in this way: (Author 2006, p.28) or (Author 2006:28). A full reference is then placed at the end of the text in an alphabetized list of "References". In article, common variations:
For a book: in the case of (Author 2005a) and (Author 2005b), this might be:
For an article: in the case of (Traynor 2005) or (The Guardian, December 17, 2005), this might be:
Footnotes
What footnotes are used forA footnote is a note placed in the proper end section of a page to comment on a part of the main text, or to provide a reference (a source) for it. Footnotes are often used to add information that might be helpful to later fact-checkers, such as a quotation that supports your edit. How to write themThe connection between the relevant text and its footnote is indicated by a number or symbol which appears both after the relevant text and before the footnote.
Example edit:
Example rendered result:
Section headingsRecommended section names to use for footnotes in Wikipedia are:
Many editors use "Notes" as their preferred title for the footnotes section, as the same section can then hold both source citations as well as general notes. Ref tags and punctuationSome material must be referenced mid-sentence, but footnotes are usually placed at the end of a sentence or paragraph. Footnotes at the end of a sentence or phrase are normally placed immediately after the punctuation, except for dashes, as recommended by the Chicago Manual of Style.[1] For example, as per the rendered result in the 'how to' section above. Some editors prefer the style of journals such as Nature, which place references before punctuation. If an article has evolved using predominantly one style of ref tag placement, the whole article should conform to that style unless there is a consensus to change it. Shortened notesWhen footnotes are used, some editors find it helpful to maintain a separate references section, in which the sources that were used are listed in alphabetical order. With articles that have a lot of footnotes, it can become hard to see which sources have been used, particularly when the footnotes also contain explanatory text. A separate references section can help readers to see at a glance the quality of the references used. When a separate reference section is included and full citations are listed there in alphabetical order, with the footnotes in a separate section entitled "Notes" or "Footnotes", then shortened notes may be used, giving the author(s), publication year, or perhaps the title, and the page numbers, in place of the full detail. Example edit:
Example rendered result:
Shortened notes using titles rather than publication dates could look like this. In any case note that the full reference is only listed once, but can be cross-referred to multiple times from the shortened notes, for example for different page references. Wikilinks to full referencesWikilinks can be created from short note citations to their matching references, thus allowing the reader to click on the shortened note and easily navigate to its appropriate full reference. See the "Further considerations" page for more details. Clearer editing with shortened notesBecause footnotes work by placing the required content inside <ref> tags within the article text they necessarily break up the text to some degree when in edit mode. Article text can become difficult to read and maintain. In this respect well referenced articles can unfortunately suffer disproportionately in comparison to those not so well sourced. In any case the disruptive effect can kept to a minimum by using shortened notes. See the "Example edits for different methods" page for some comparative examples using shortened notes and full length references in footnotes. These offer representations of edit mode views with examples of how they render to the reader. Embedded links
Web pages referenced in an article can be linked to directly by enclosing the URL in square brackets. For example, a reference to a newspaper article can be embedded like: [http://media.guardian.co.uk/site/story/0,14173,1601858,00.html], which looks like this: [1] A full citation is also required in a References section at the end of the article.
which appears as:
Citation templates
The use of citation templates is neither encouraged nor discouraged. Templates may be used or removed at the discretion of individual editors, subject to agreement with other editors on the article. Because templates can be contentious, editors should not change an article with a distinctive citation format to another without gaining consensus. There are (at least) two families of citation templates. The {{Citation}} template is intended to provide citations for many types of references. The other family has names of the form {{Cite xxx}} (for example, {{Cite book}} and {{Cite web}}). These two families produce different citation styles. For example, the "Cite xxx" family separates elements with a full stop, and gives page ranges as plain numbers, while the "Citation" template separates elements with a comma, and precedes page ranges with "pp." Thus, these two families should not be mixed in the same article. Reference qualification in article textMatters of a fairly uncontentious nature do not necessarily require further qualification in the article text apart from their references. No further description would be needed with the following, for example:
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