# How should I cite something learned second-hand (eg, from Wikipedia) when I haven't seen the primary source?

I want to cite something that I have learned from a Wikipedia page. However, I'm loathe to cite Wikipedia because of the perception of it by my tutors, so I try to cite the original source.

What should be the correct thing to do when I'm unable to have sight of the primary source myself, or find it in a collection (for clarity, I should add that I have the details of the source - I just can't find it in collections available to me)? Should I just cite as much original information as I can, or should I defer to citing Wikipedia? I'm hesitant to do that, because a glance at the citation would suggest that I was 'too lazy' to source original material or just dig deeper.

For additional clarity - I know that citing Wikipedia is 'bad' etc. The emphasis is on how to cite something that has been learned via Wikipedia (as an example) but for which the original material cannot be seen or retrieved from available collections or searches.

• Why can't you look up the original source? – JeffE Feb 4 '13 at 14:39
• @James The FAQ assumes graduate-level research, so questions will be approached from a graduate-level perspective. Certainly some questions apply to both undergraduate and graduate work (as this question seems to do), but my understanding is that some level of applicability to graduate-level work is a requirement for academia.SE. – apsillers Feb 4 '13 at 19:18
• Some information on Wikipedia is highly specialised, but some information is quite "commonly known". If the information is sufficiently commonly known, you can get away with citing nothing at all. For example, you don't need a citation for "The Earth revolves around the Sun.". – gerrit Feb 4 '13 at 19:28
• This isn't a postgrad research question - it's way too junior. And thus off-topic for this site. Voting to close. – EnergyNumbers Feb 4 '13 at 21:17
• @EnergyNumbers there is nothing in there specific to undergrad studies, so I think it's on topic. Just because the answer is not very complicated doesn't mean it's not a valid question people might ask… And I think this one is a valid question, and on-topic. – F'x Feb 5 '13 at 9:34

What you're referring to is an indirect source. In general, you should always work as hard as you can to find the original source. If that is not possible, all of the major style guides include a way to cite indirect sources. Note that you should not cite Wikipedia (see the "do not cite Wikipeida" note at the end of this answer). If an indirect citation is absolutely necessary, it should come from a reputable, peer-reviewed journal or other academically respected source.

1. According to Purdue University, the MLA rule is to name the author of the indirect source in the text and cite the work you have in-hand:

For such indirect quotations, use "qtd. in" to indicate the source you actually consulted. For example:

Ravitch argues that high schools are pressured to act as "social service centers, and they don't do that well" (qtd. in Weisman 259).

Note that, in most cases, a responsible researcher will attempt to find the original source...

Williams College further clarifies that the indirect work should be included in your Works Cited list:

...include the indirect source in the Works Cited.

2. The APA rule (also from Purdue University) is to exclude the indirect source (called the "original source", below) from your reference list and only include the work you have in-hand (called the "secondary source"):

...name the original source in your signal phrase. List the secondary source in your reference list and include the secondary source in the parentheses.

Johnson argued that...(as cited in Smith, 2003, p. 102).

[...] Also, try to locate the original material and cite the original source.

3. The Chicago rule (once again, from Purdue) is to cite the indirect source, followed by the in-hand resource:

...Chicago discourages the use of [indirect sources]. In the case that an original source is utterly unavailable, however, Chicago recommends the use of "quoted in" for the note:

1. Ian Hacking, The Social Construction of What? (Cambridge, MA: Harvard University Press, 1999), 103, quoted in Manuel DeLanda, A New Philosophy of Society (New York: Continuum, 2006), 2.

That said, do not cite Wikipedia in a formal document (unless, perhaps, you are actually writing about Wikipedia or collaborative editing techniques). I love Wikipedia, and I believe it is reasonably well-maintained and has a lot of good information. However, you have no way to verify if the information in an article is true -- or, if you do have a source to verify it, you would just cite that source. Aside from the tired, "Anyone can edit it!" complaint, two severe issues with Wikipedia as a citation source are:

• You get whatever version of an article stands at the exact moment your web browser fetches the page. No matter how hard Wikipedia's editors work, they can't stop a bad edit from reaching your web browser if it was made seconds before you fetched the page. Wikipedia doesn't undergo any kind of pre-publication review; all review is post-publication, which means you may see totally unreviewed information. (You can mitigate this by citing a specific past revision, but it still stands that a post-publication review process means that any given revision of an article could have claims that have been reviewed by absolutely no one except the author.)
• In order for a reader or reviewer to ascertain the usefulness of a source, it must have an identifiable set of authors (or, for anonymous works, at least a consistent, reasonably small set of authors). Wikipedia makes that requirement incredibly difficult to satisfy. (Again, it's possible to satisfy this requirement if you cite a specific revision of a page and find out what contributors wrote each part of a page, but it is still difficult since a potentially huge number of contributors have helped build that revision.) It's hard for a Wikipedia article to be reputable where there are no clearly identifiable authors to which a reader could attach a reputation.

First, I would try harder to get the primary source. Really. But, if that isn't possible (price, availability, etc.), you may have to do without. In that case, a few solutions:

• Find another secondary source, possibly one that is more “academically acceptable” than Wikipedia. For example, try to find a textbook on the topic that make mention of the fact you want to source, or a review article, a book, etc.
• If not possible, what I have usually seen people do is cite the primary source anyway. That's bad, but people do it. If you write for a journal, where the reviewers might not allow a reference to Wikipedia, you might not have any other choice.
• What I would recommend, if the format and/or editor allow it, is to cite both the primary source and the secondary source, possibly indicating the relationship:

J. Doe, Journal of Failed Experiments 10, 1024-1028 (1971); as cited by secondary source

Note: This is written from the perspective of a postgraduate student in applied mathematics.

1) Do not cite Wikipedia.

This is not about perception or laziness but rather, your thought process as a researcher. Suppose I read about a mathematical fact that might be useful to my research. I need to verify that the fact is true and have some ideas about why this is true.

By stating that the mathematical fact has been published in a reputable peer-reviewed journal or in a reputable textbook, I demonstrate that I have at least verify its authenticity, and perhaps even read technical details about it.

However, if I cite Wikipedia, it demonstrates that I accept facts off the internet without verifying or having technical understanding about it (Wikipedia usually don't go into deep technical details). This does not bode well for my reputation as a researcher.

2) Try to find an academically acceptable source to cite the same information from.

Suppose I want to use an equation. Random example: Kullback-Leibler Divergence. But lets pretend there is no source or citations on Wikipedia.

What I will do is to search directly for "Kullback-Leibler Divergence" using search engines like Google, Google Scholar or Google Books. I will also try to search for the term in my university or local library's search tool.

Assuming this fails. Then, I would look at topics that the Kullback-Leibler Divergence is in or is related to. For this specific example, I would look for textbooks or materials on "Information Theory" and look up their index or table of contents for "Kullback-Leibler Divergence". If this fails, I will dig deeper: think about what this equation does and search for similar topics. For this example, it compares two probability distributions. I will then look for ways to compare two distributions in Information Theory.

Once I find a paper or textbook talking about it, it shouldn't be too difficult to locate the source or pick a suitable paper/textbook to cite the equation from. If after all these searching and perhaps asking my supervisor/professor, I cannot find anything acceptable to cite from, I would ask myself these questions: Is this equation valid? Why should I believe in the authenticity of this equation?

• #1 says it all, never cite wikipedia – nathan hayfield Feb 5 '13 at 0:46

I don't think you can cite something to which you have no (original) source. I mean anyone can edit Wikipedia (or any other similar webpage) so that would practically be citing a random person, without any way for a third party to check up.

Luckily Wikipedia articles usually have references you can check (to see whether or not they are actually accurate and relevant) and cite accordingly. If there is no reference then you should probably not be citing (or trusting) that piece of information.

• Wikipedia is not really citing a random person, but rather citing a collective opinion by a random group of people (although there is probably a big bias caused by the fact that you probably only edit an article you feel you have knowledge about). But I agree that external references, preferably peer reviewed, are needed. But in general, the level of Wikipedia is ok. – Paul Hiemstra Feb 4 '13 at 16:38
• perhaps I didn't make myself clear enough. Without a valid source, anything on wikipedia could be a random person claiming a particular piece of information. That kind of info will eventually get cleared out by the community but it might just be so that you retrieve the "misleading" info before someone with more insight on the matter corrects the article. – posdef Feb 4 '13 at 16:51

In addition to many good points made in other answers: while I agree that Wiki is not an acceptable final "authority/source" for nearly anything, the better articles do give external references that can put one onto the right track for more primary sources, as well as giving internal links via other keywords... As to how-to-cite, I have gotten more and more into the habit of at least footnoting that I found a reference (to a primary source) via Wiki.

Yes, of course, in one's primary "specialty", one should have better pointers to the "official" literature than Wiki, but with regard to necessary but peripheral topics for one's work, often Wiki can provide hints, which can then be verified afterward, after one has become aware of them.

So I use Wiki to begin to get a grip on keywords and vague ideas in things unfamiliar to me, to get started. Also, sometimes historical pointers are more readily accessible there, and then subsequently verifiable on MathSciNet, after one knows what to look for.

I note that "peer-reviewed" stuff should also be viewed skeptically/critically, especially with regard to recognition of prior art, and also simple correctness, since except for significant results, often referees are encouraged to not worry about certifying correctness, but more "novelty" and "interest". And history and prior art are often either omitted due to disinterest or ignorance, or pushed out by editing-down considerations, so that papers often do not give an effect look "backward".

Finally, in the spirit of giving credit where credit is due: when I find Wiki useful, I don't pretend that I didn't! Not that I view it as authoritative, either. A new category of information, perhaps.

Note that if the Wikipedia article doesn't have the original source for a claim, then that section of the article is a work in progress that is below the Wikipedia standard. It requires a {{citation-needed}}, otherwise it could be "original research" which properly doesn't belong there.

It's probably a bad idea, in your academic paper, to quote Wikipedia material which the Wikipedia itself disavows!

There should never be a need to cite the Wikipedia, since anything credible is supposed to have references to the outside. In serious work, you always borrow the citations from the Wikipedia, not the text. Citing from the Wikipedia itself is good for cafeteria arguments.

When you make any kind of citation, you are basically expressing trust in the author. This is because you are not reproducing all of the research, such as experiments. You trust that the data haven't been falsified and so forth. There is some safeguard in that the paper appears in some trustworthy publication, and that it has been peer reviewed.

Suppose that the Wikipedia is actually the only source for some paper. Firstly, that situation is wrong and blatantly violates the Wikipedia's rules about original research, so the page will probably be deleted. Secondly, the Wikipedia isn't a journal that reviews and publishes material, so you would have to take that paper completely at face value. The Wikipedia cannot lend any credibility to anything, according to its defined mission and scope.

• +1 for "there should never be a need to cite Wikipedia." If it's not supported with valid evidence, then there is no reason to believe it is true. – earthling Feb 5 '13 at 1:38

If you consider citing Wikipedia, don't, as others have explained, but IMHO you should at least acknowledge it as being helpful, either with just a mention like that or a list of "non-cites" that could be used as starting points for others wanting to review Wikipedia's (latest) views on your topics.