If an article, theorem, etc. is unpublished, presumably the work is only available to people who track down the author and get a draft copy. Today we have arXiv and can find many preprints on the Internet, but people have been citing unpublished works longer than arXiv has been around. It seems like an unscrupulous author could claim anything he wants, cite an unpublished work that doesn't support his claim (or even one that doesn't exist), and get away with it unless the bad claim is caught in the review process.

I suppose the reviewers could ask for a copy of the cited work, but I recently saw a citation that was just "private communication 1981" for a paper published in 1985, and that could easily have been a phone call where no record could be provided to a reviewer.

I've never published anything myself, so maybe I'm unaware of a part of the review process that is meant to catch this, but what prevents authors from making bad citations of unpublished works?

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    How is this different from citing an obscure book? Just because the content isn't easily available, doesn't mean it can't be cited.
    – Mast
    Apr 29, 2020 at 13:07
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    @Mast What do you mean by an "obscure book"? I assume that your obscure book went through a refereeing process and so it is, most obviously, completely different from an obscure phone call and in fact from any phone call. It is crucial not to write nonsense such as "private communication 1981" in the references (in other places it is basically acceptable, we can live with that).
    – John B
    Apr 29, 2020 at 13:44
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    @JohnB why do you assume that "book went through a refereeing process"?
    – Dan M.
    Apr 29, 2020 at 15:02
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    @JohnB There's nothing inherent with books that implies it should be refereed. Of course, books published by a reputable publisher should undergo copyediting process, but that's not peer review. Though obscure books published by a proper publisher in most countries should at least have a legal deposit available; so not completely unobtainable from a third party, compared to unpublished private communications etc..
    – xngtng
    Apr 29, 2020 at 16:28
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    For the record, I have contacted someone who was listed in a "private communication" citation before and asked for an explanation of the cited content, and they were happy to oblige. While that's not always possible, its not as if that entire class of source material is definitively unobtainable. And as others have pointed out, if you got an idea from someone else, you have to credit them for it, even if it was private communication. Apr 30, 2020 at 19:17

7 Answers 7


You seem to be interpreting citations as a way of proving something by appeal to authority. That is not what citations are. A citation is a way of giving appropriate credit to the originator of an idea and pointing the reader to the explanation of that idea. Not giving credit to the person who gave you an important original idea is unethical, whether that idea has been published or not.

Citing a "personal communication" related to a mathematical fact (for instance) does not eliminate the need to prove that fact. Appropriate usage would be to write something like "the following was communicated to me by X. Y. [personal communication]", followed by (for instance) a theorem statement and its proof.

Note that if something is in a technical report or on arXiv, it is not unpublished. People publish blog posts, novels, and Youtube videos. Published and peer-reviewed are completely different things and it's wrong to conflate them.

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    I interpret citations in two ways: 1. to give credit to the originator of an idea, and 2. to provide further reading to the reader (e.g. for details not pertinent to the current paper, but which the reader might be interested in). Maybe the second point is me assuming too much, but it seems that every other form of citation satisfies both points.
    – zaen
    Apr 29, 2020 at 6:20
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    Whether something is an appropriate source of information and wheather you should cite it are two different things. The problem with citing YouTube videos is not that you shouldn't cite YouTube if you got something from there, but that you shouldn't be getting your information from YouTube. Apr 29, 2020 at 20:47
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    A YouTube video surely beats "personal communication" as a source, and a YouTube video of an academic conference could be a decent source.
    – prosfilaes
    Apr 29, 2020 at 23:50
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    The bigger problem with citing YouTube videos is that they vanish too easily. Apr 30, 2020 at 5:41
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    Also, a citation doesn't mean that you regard the cited work as the objective Truth. One might even cite results which have since been proven to be wrong, if you need them as an example, or you need to discuss the shortcomings of the methods they used and show how to improve them. Because even "wrong" results can be useful as building blocks to build something better (or to demonstrate the shortcomings of a method in favor of another), and if someone already did the groundwork, why not use it? Or of your work is about disproving an old theory, you have to cite the old theory you are refuting.
    – vsz
    Apr 30, 2020 at 8:26

What's the alternative? I can only see two:

  • Don't write the text. This would also mean you have something worth sharing, but are not sharing it. This goes against the purpose of publishing in the first place.
  • Write the text, but don't cite it. That's plagiarism.

Since the alternatives are undesirable, it's acceptable to cite unpublished works.

  • 'Don't write the text. This would also mean you have something worth sharing, but are not sharing it. This goes against the purpose of publishing in the first place.' this seems like a logica non sequitur. It isn't ones to share (it is someone else's) and needs to go through peer review first.
    – Tom
    Dec 13, 2023 at 5:18

An answer by David Ketcheson highlights the importance of giving credit for ideas as a reason for citing unpublished works.

Another reason for citing unpublished works can be grey literature. The linked Wikipedia article describes the history of grey literature coming out of World War II, when the Allies produced a large amount of nuclear research that was not formally published, but still scientific important.

In my personal experience in applied ecology, grey literature can be an important source for management decisions and data. For example, a wildlife preserve manager might do controlled burns every 5 years based upon their wildlife preserve's local monitoring program. But, they would not formally publish their work as an article. Instead, they might summarize their work as part of a report that lacks peer review. However, a researcher studying fire ecology might describe the wildlife preserve's management as part of a peer review article or describe trends at the preserve.

More broadly, nuance is key to understanding what is acceptable to cite. First, different academic fields have different general expectations for how to cite non-peer reviewed science and journals usually have a distinct citation style (e.g., inline vs reference section). Second, a nuanced view is important for what is being cited. Citing facts, observations, and applied choices differ from citing conclusions.

Last, to answer your final question, what prevents authors from making bad citations of unpublished works? Nothing. But, a nuanced view of peer-reviewed articles helps here. Just because something is peer-reviewed, it is not infallible. Additionally, I've had authors make bad citations of my published works. I've joked I sometimes learn new things about my research by reading work that cites it.


A complement to the good answers already here:

Giving people credit for the ideas they bring to you, by whatever means available even if not ideal, signals to possible future collaborators that it's safe to bring other ideas to you. Safe in the sense that you're not just going to let people assume you're the source of the idea.

If widespread enough, the practice of citing by whatever means available signals that it's safe to bring ideas to the community without worrying about first getting proof that it's yours. That's established to some extent in the scientific community, and we all should contribute to keep it going.

There's a lot to be said about the advantages of exposing preliminary results, doubts, even half-formed ideas to colleagues, even those who are otherwise strangers. That's most of the point of conferences.


What does harm research progress is quoting any literature without having read it or dropping citations for the bang of it. There, sloppiness or bad faith are disguised under the shine of a DOI or ISBN. Anything that is not peer-reviewed, and reported as such, will be looked at at face value and put in perspective: let writers write critically, let readers read critically.

As others point out very well down this post, the crux is doing justice to the others' work, conscientiousness and creativity, in accordance with their own job specifications.

Off-note. Once you mention you are new to publishing, among countless resources, you might find it interesting to read the science pages that the British newspaper The Guardian dedicates, with some regularity, to peer review and scientific publishing. It is sometimes useful to have journalists looking at science. These ones among and along others.


(To add to the already good answers. I'll assume math, since you mention "theorem" and "arxiv", but this probably applies way more in general)

What would "get away with it" mean here? Publishing is not a magical process that endows the published article with an indelible aura of perfection for the ages. Publishing is just the (usual, normal, common, accepted) way of disseminating one's research. If someone's research is wrong, this will be known rather sooner than later.

Papers are most often refereed by people who are experts in the topic, so getting away with claiming something outrageous from an obscure source will not get you very far. The more important the journal, the more true this is.

Also, research is not something that happens in a vacuum. There is a community. If you are doing something that is not related to anything anybody cares about, and you publish in bad journals, you can probably "get away" with almost anything. But a normal researcher cites people, talks at conferences and meets those people, themselves and their work become known. Those "mysterious preprints" form the past were available to anyone who asked (you would send a letter to the researcher and get a copy, that was standard back then). So, the people who cared about those preprints did have them.


I think if a work is not unpublished, there is no such thing as "cite", it is merely mentioning. But I do think it is important to do so.

First, when you make a scientific argument in your work, you always need evidence and support. Mentioning unpublished work tells readers that what you are talking about is true, and they will keep it in mind and go to validate it when you actually publish it.

The second is that to show others you are the first one to make these discoveries, but you have not published it yet. This is important in academia as well.

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    "if a work is not unpublished, there is no such thing as cite" <- I think you may have included more negatives than you intended to here.
    – Anyon
    Apr 30, 2020 at 23:16

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