Sources
Wikipedia reliable sources: what counts and what does not
Sources decide whether an article is accepted or deleted. Here is how Wikipedia judges news articles, interviews, press releases and books, with a checklist to assess your own.
Key points
- A useful source for Wikipedia is published, verifiable, reliable and independent of the subject.
- Notability needs sources that cover the subject in depth, not passing mentions.
- Official websites, press releases and sponsored content can verify simple facts but never prove notability.
- Printed sources are fine as long as they are cited completely.
On Wikipedia an article is only as good as its sources. The verifiability policy requires that material can be checked against published sources, and the notability guidelines require that the subject has already been covered by reliable, independent ones. Here is how to tell the sources that hold up from those that get an article deleted.
Four questions to ask of every source
- Is it independent? The author must have no connection to the subject: no employees, investors, clients, sponsors or PR agencies.
- Is it reliable? A publisher with editorial oversight and a reputation for accuracy. See Wikipedia's reliable sources guideline.
- Is it significant? The subject must be discussed in depth, not just named in a list or a single line.
- Is it secondary? It must contain someone else's analysis or synthesis, not only the subject's own words.
A source that passes all four helps establish notability. The others can, at most, verify uncontroversial details.
Concrete examples
| Type of source | Establishes notability? |
|---|---|
| In-depth feature in a national newspaper by a staff journalist | Yes, the ideal source |
| Book from an independent publisher with a chapter on the subject | Yes |
| Academic paper analysing the subject's work | Yes |
| Interview in a reputable outlet | Partly: it verifies facts, but the subject is speaking |
| Trade magazine article | With caution: there is a presumption against trade press for companies |
| Local newspaper | Weak: useful for details, rarely for notability |
| Press release, even if republished on many sites | No |
| Sponsored or paid article | No |
| Official website, social profiles, personal blog | No |
| Self-published book | No |
Common traps
- One press release on twenty sites: still one source, and not an independent one.
- Contributor posts on platforms without real editorial control: Wikipedia keeps a list of perennial sources that flags many of them.
- Passing mentions: "companies such as X attended" does not cover X.
- Routine announcements: hires, funding rounds, new offices, trade fair appearances.
- Coverage of the wrong subject: an article about the company does not make the founder notable, and the reverse is also true.
How to cite a source
Every citation should let anyone find the source again. Always include:
- author and title of the article or book;
- publication or publisher;
- date of publication, and page for printed sources;
- URL and access date, for online sources.
Online sources disappear: save an archived copy, for example on the Internet Archive, and cite it alongside the original. Printed sources are not second-class: a 1998 article in a national newspaper is as good as one from today, as long as it is cited properly.
Checklist before writing
- Do I have at least three independent, reliable sources that cover the subject in depth?
- Do they reach at least a regional or national audience, and are they spread over time?
- Have I removed press releases, sponsored content and material produced by the subject?
- Does every important fact I want to write have a source?
- Do the sources actually say what I will write, without stretching them?
If the answer to the first question is no, the problem is not the writing but notability. If it is yes, move on to creating the article.
Not sure how to judge your sources? In our free check we look for them among public sources ourselves.
Frequently asked questions
Is an interview a valid source?
An interview in a reputable outlet can verify some facts, but it is the subject speaking about themselves. Notability needs pieces in which journalists analyse the person or company.
Do sources have to be online?
No. Books, newspapers and printed magazines are fine as long as they are published and verifiable: cite them with author, title, publication, date and page.
How many sources do I need?
There is no fixed number. Quality and independence matter: a few reliable sources covering the subject in depth outweigh dozens of passing mentions.