I'm currently writing my master's thesis and I've gotten some good answers that have helped me along in my process.

My question is, do I cite Mathematics Stack Exchange in my thesis or do I put a note of thanks?

One thing to note is that posts on the site can be edited at any time. It's not like citing a paper: You know its content will never change. –  becko Jun 11 '12 at 3:39

4 Answers 4

up vote 24 down vote accepted

There was a discussion on meta.mathoverflow about this, How do I cite Math Overflow?

I agree with what Mike Shulman suggested, which is putting a sentence in your acknowledgements:

If the answers came out of a large discussion, then I think acknowledging MO as a whole might make sense (though I might still mention explicitly the main contributors, if possible), but if the answer came from a specific person, I would acknowledge that person (and perhaps say that the answer was given on MO).

Also, as pointed out by Noah Snyder on that meta post, this paper does a reasonable job citing math overflow, and the main answerer, in footnote 8.

Could you please explain how I acknowledge if the user does not use the real name? –  triomphe Jul 8 '14 at 13:53
@triomphe: presumably, you could treat it in the same way as a referee. "We would like to thank an anonymous referee for their helpful comments" / "We would like to thank an anonymous contributor to Mathematics Stackexchange for the idea that led to Theorem 4". –  Carl Mummert Sep 15 at 16:31

I too have this issue coming up. One part of my thesis began on this site and another on MathOverflow.

My intention is to put a footnote link to the threads, give credit when I use someone else's proof which appeared on these sites and of course give thanks both to the communities and the users (by real name if possible, by user name otherwise) - both those who asked the question; gave helpful comments and so on.

"Acknowledgements: [..] I'd also like to thank Moron, Anon, and User1234." :) –  user2468 May 20 '12 at 15:38
Well, not exactly... but not that far away I suppose. –  Asaf Karagila May 20 '12 at 15:53
And extra special thanks to victor –  The Chaz 2.0 May 20 '12 at 16:17
@J.D. That is an incredibly awesome comment. –  Eugene May 21 '12 at 3:12
@Eugene what are the odds! I also go to UW. –  user2468 May 21 '12 at 3:52
@J.D. Reminds me of the references on this MW article. –  anon May 21 '12 at 4:56
Footnote link to the threads? Why not just cite it? –  Willie Wong May 21 '12 at 7:43
@Willie: for the same reason you would prefer arXiv or journal or homepage PDF. Plus my advisor will disapprove, I already had this chat with him... –  Asaf Karagila May 21 '12 at 7:46
"Plus my advisor will disapprove" Ah. that explains it. I would however encourage the OP to have "the talk" with his/her advisor and see whether citing an online resource is ok. –  Willie Wong May 21 '12 at 7:53
@Willie: I think that MO and MSE are discussion sites, much like you would not cite a coffee chat with colleagues or an email correspondence. I do think that since the site is open to all it is fine to address the discussion and add a link. I still don't see a justified cause for a citation in the bibliography (at least in the case of my thesis). –  Asaf Karagila May 21 '12 at 7:58
"I would not cite a coffee chat with colleagues or an e-mail correspondence". Really? I certainly would. I would usually cite them a "private communications". This is, of course, not a way to let readers check those citations, but as a way to give credit where credit is due. –  Willie Wong May 21 '12 at 8:08
Clarification: I would cite them as I would cite a paper. In the text it would read "blah blah [13]" and in the bibliography it would have "[13] Joe the plumber, private communication". Part of this, of course, has to do with personal aesthetics. And I think we can agree to disagree. As a couple of parting shots, however: see Emerton's and Kostya's answers and comments thereon where both opinions are expressed. –  Willie Wong May 21 '12 at 8:29
See Chartier's thesis here: caicedoteaching.wordpress.com/students for how a student of mine dealt with this. –  Andrés Caicedo May 21 '12 at 22:06
@Andres: Perhaps this should be posted as a separate answer? –  Asaf Karagila May 21 '12 at 22:17
@Willie Wong: not all journals will even allow "private communication" as a reference in the references section - they may limit references to those which are formally published and disseminated. If the journal also forbids footnotes (some do) then the best option may be to just name-drop the person in the text of the paper. That is still a formal acknowledgement of their work, but many people don't call it a "reference" if it is not in the references section. –  Carl Mummert Sep 12 '13 at 13:36

It might be noteworthy, that the site now has a handy "cite" feature below each post on main wich creates copyable BibTeX and amsrefs citations for the respective post. It can be reached by clicking the "cite" button (between "share" and "edit").


According to the terms of service, paragraph 3, subscriber content:

In the event that You post or otherwise use Subscriber Content outside of the Network or Services, with the exception of content entirely created by You, You agree that You will follow the attribution rules of the Creative Commons Attribution Share Alike license as follows:

  1. You will ensure that any such use of Subscriber Content visually displays or otherwise indicates the source of the Subscriber Content as coming from the Stack Exchange Network. This requirement is satisfied with a discreet text blurb, or some other unobtrusive but clear visual indication.
  2. You will ensure that any such Internet use of Subscriber Content includes a hyperlink directly to the original question on the source site on the Network (e.g., http://stackoverflow.com/questions/12345)
  3. You will ensure that any such use of Subscriber Content visually display or otherwise clearly indicate the author names for every question and answer so used.
  4. You will ensure that any such Internet use of Subscriber Content Hyperlink each author name directly back to his or her user profile page on the source site on the Network (e.g., http://stackoverflow.com/users/12345/username), directly to the Stack Exchange domain, in standard HTML (i.e. not through a Tinyurl or other such indirect hyperlink, form of obfuscation or redirection), without any “nofollow” command or any other such means of avoiding detection by search engines, and visible even with JavaScript disabled.

To summarize, unless you created the content, you must clearly link to the post, link to author, and identify it comes from XX.SE site. This may seem like a pain but it can be a benefit if SE every has a math careers or academic careers associated with the sites that are academic in nature such as chemistry, biology, math, etc. The linked research content could then be added to userX's careers profile which in turn could help them land a first career or a new career.

Additionally, in the other answers, it mentions real names and only usernames if that is all they have; however, this practice would not follow SE subscriber content. You can put their real name if you know it but you must link to their profile with their user name.

Here is the screenshot from the accepted answer of the paper that does a "reasonable" job.


This would not be the correct way to cite subscriber content obtained from SE.

Here is how I cited the use of a LaTeX diagram:

enter image description here

I believe the situation is more complex. I agree that if you actually use text or code, as you did, this applies. However, if you just cite, then you can cite in another way. Compare to traditional publishing: if one needs to cite a paper one just does it in the usual way and does not need to worry about copyright; if one wants to include parts of another paper, say graphics, in ones paper one might need to check with the copyright holder. What you mention is the analog of the latter. –  quid Mar 17 at 16:27
@quid If I received help from another user with a proof or some result I didn't come up with on my own in a paper, I would have to cite with a link to the user and post per the legal site terms of SE. My blurp from the ToS is for SE terms not SO so this applies network wide. However, the examples used are from SO. –  dustin Mar 17 at 16:38
@quid actually no one has to cite, but if their paper becomes widely recognized and the user who helped with it via SE sees there work un-cited, they could contact SE who could take action since they will want to be recognized for bringing together the writer of the paper and the person who helped solve some part of it. If that is the risk someone is willing to take, the onus is on them. Everything we post on SE becomes subscriber content. If we use content that isn't ours, we have to adhere to the definitions SE lays out in legal. –  dustin Mar 17 at 16:46
I am not convinced this is the case. I believe (but really it is only a believe) as soon as I rewrite it in my own words, I do not "post or otherwise use" subscriber content in the sense intended there. I'd still have to quote the source, but for a different reason. –  quid Mar 17 at 16:48
@quid if you write in your own owrds: Attribution — You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use. This is from CCASA that SE uses. –  dustin Mar 17 at 16:58
"You do not have to comply with the license [...] where your use is permitted by an applicable exception or limitation." Then "Do Creative Commons licenses affect exceptions and limitations to copyright, such as fair dealing and fair use? No. By design, CC licenses do not reduce, limit, or restrict any rights under exceptions and limitations to copyright, such as fair use or fair dealing. If your use of CC-licensed material would otherwise be allowed because of an applicable exception or limitation, you do not need to rely on the CC license or comply with its terms and conditions." –  quid Mar 17 at 17:05
Then "Fair use is a limitation and exception to the exclusive right granted by copyright law to the author of a creative work. In United States copyright law, fair use is a doctrine that permits limited use of copyrighted material without acquiring permission from the rights holders. Examples of fair use include commentary, search engines, criticism, parody, news reporting, research, teaching, library archiving and scholarship. It provides for the legal, unlicensed citation or incorporation of copyrighted material in another author's work under a four-factor balancing test." It's not so clear. –  quid Mar 17 at 17:06
@quid you are talking about permission. Citing isn't asking for permission. Let's agree to disagree then but remember that SE has more money, more lawyers, and if they feel they weren't giving due credit, they have the means to go after individuals and computer forensics can determine if someone visit a site, saw a page, and if they did this prior to publishing some paper with information from that site, it will be hard to say I didn't take any information from that page so I didn't need to cite. Is that the risk you want to take? –  dustin Mar 17 at 17:10
I started by saying the situation is more complex. :-) I honestly do not know what is actually the case. However, it would seem quite odd to me that if I cite a CC-licensed thing, I would have to comply to a lot more rigid restrictions then when I do the same for a thing under copyright by a commercial publisher. But perhaps this is the case. –  quid Mar 17 at 17:16
The idea that it would be necessary to include a URL in a research paper because one encountered a fact on a website is not in agreement with actual citation practice in mathematics. Fortunately, there is no real conflict, because "using subscriber content" means reusing content from this site, not merely referring to content from this site. Mathematical ideas (apart from the literal words that are used to express them) are not covered by copyright. –  Carl Mummert Sep 15 at 16:21

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