# If I use a result from Wikipedia, how should I cite that result?

I am writing a short article on the $\zeta$-function, and I use the "Rising factorial" representation of the function in the article. You can see that in that here. Now there is no citation in wikipedia concerning that identity. So, if I use that identity in my article, how should I cite that?

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@yoyo: Not so. To take a trivial example, if you're writing an article about mathematics education and want to discuss the way popular textbooks and Wikipedia treat a topic, you would cite Wikipedia. :-) If the short article you're writing is roughly at the level of a blog post, again there's no harm in citing Wikipedia. If you have read and liked some treatment on Wikipedia and want to, on your own authority, recommend it to readers, then also it's fine to point to it. Etc. And "it might change" is precisely why you should link to a specific version; it's not a reason against citing WP. – ShreevatsaR Jun 4 '11 at 6:53

Ideally, Wikipedia would link to a source for the result, the source would be accessible to you, and you could cite it instead. But it often happens that Wikipedia doesn't have a source. In that case, be warned that Wikipedia may be wrong. In any case, many people do not consider Wikipedia an acceptable source. But if you want to cite Wikipedia anyway (you're sure the result is right, or it's an informal article, or you're specifically pointing out how something is treated on Wikipedia, etc.), Wikipedia has tools showing you how to cite it. In the left sidebar of Wikipedia, under "Toolbox", the last link is called "Cite this page".

Click on it. You'll be taken to a page like this which tells you how to cite it in various formats (APA style, MLA style, etc.), including (most useful if you're using LaTeX) the BibTeX entry. It also gives you a permanent link to the version as you saw it, so that even if the section is later changed on Wikipedia, those who follow your citation will see exactly what you saw (assuming of course that the article itself doesn't get deleted).

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If I were you, I would search the literature for a citation from a different source. Wikipedia is usually not considered "good" source for citations.

If you insist, I would have cited it as:

"Riemann zeta function", Wikipedia, the free encyclopedia, http://en.wikipedia.org/wiki/Riemann_zeta_function#Representations

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