I am writing a review article and have come across a number of references which were published verbatim in their entirety in more than one place (same author(s) and the same content; Duplicate Publications). All of the publications in question are before 1970 and may be divided into two classes: those that have an instance with a statement that the content has been published or presented elsewhere (which references the duplicate) and those lacking such a statement.

For those with a statement, I am inclined to cite the earliest instance and omit the later. However, the approach is unclear for those where precedence is not apparent.

I am looking for any recommendations (best practices, examples) on how citing duplicate publications should be handled in general. I have not come across an example in my literature review and have been unable to find any guidance (most search results are related to preventing duplicate publications rather than coping with their aftermath decades later).

Options I see at the moment (some of which are more palatable than others):

  1. Don't explicitly acknowledge the duplication, but cite both variants in the text and bibliography (i.e., a parenthetical or textual citation with both instances each and every time I want to reference its/their content).
  2. Pick one (randomly if precedence cannot be determined) and ignore the other.
  3. Pick one (randomly if precedence cannot be determined) and include a footnote at the first use indicating that another instance exists (the alternative instance would be cited there with the full citation included in the cited references section).
  4. Pick one (randomly if precedence cannot be determined) and modify the full citation in the cited references section to indicate that another instance exists and provide the full citation of the alternative.

Some additional, possibly relevant information:

  • Subsequent publications are inconsistent in which instance is cited (i.e., both are cited and precedence is often ignored).
  • The field is environmental biotechnology.

Edit: To clarify in response to BioGeo's answer, I cannot determine absolute precedence for instances lacking a statement because the submission dates are not included (apparently the practice was not yet common, at least in this field). Unless there is a "standard approach" of which I am unaware, the published date cannot be relied on as a general solution either, given the differing precision in reported dates. For example, consider a duplicate publication where one instance is a book chapter published in 1943 and another instance is an article in the June issue of a journal published the same year. Which came first?

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    I would assume this to be covered in the various citation-styles, so I added the tag. However, I couldn't find anything in the APA Publication Manual Table of Contents, nor on the APAStyle blog. Dec 3, 2016 at 8:23
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    I guess I would treat it like the translated Russian physics journals, with the translated version published by the American Physical Society. There one would reference the original Russian, then in parenthesis give the translated version reference.
    – Jon Custer
    Dec 5, 2016 at 22:50

6 Answers 6


The purpose of references is for readers to look up the sources of the information you present in your article. If these publications are exactly the same, word for word, then I would not worry too much about it and I would cite the most easily accessible source or the one with a DOI and only cite it once, so that it will be easier for readers to find the source without having to access some articles that are published in less accessible journals.

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    That's what I'd recommend, too. Additionally, a footnote mentioning the duplicate publication would not hurt.
    – Dirk
    Dec 6, 2016 at 0:16
  • Thank you for your answer. I awarded the bounty to you because none of the answers satisfied the bounty request but yours told me what I probably need to hear (that I'm worrying about it too much). That being said, I do find "accessibility" to be uncomfortably subjective (few of the references have a DOI and many of the journals are now defunct, meaning availability in print depends on the holdings of one's library or its participation in loan programs). Moreover, if accessibility is the objective and the purpose of references as you say, wouldn't listing all of the instances be preferred?
    – Guho
    Dec 12, 2016 at 21:23
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    @Guho I understand what your problem is, but I don't think accessibility is that subjective, while not everybody has a huge library, more and more articles are available online through different channels, and you can check if something is available or not. But I would agree that if you include a list of duplicates it might help find at least one of them. Dec 13, 2016 at 14:30

As a review article should not also give a broad overview of developments in a certain research field, but also ease the task to anyone who wants to get acquainted with the history of research on a certain topic, you should provide all the information that may help your reader. If a certain seminal piece of research was published twice under different names I as a reader would profit from the knowledge that these are essentially the same text, which would save me from having to figure it out myself. So I would recommend citing both versions and explicitly stating that the works are identical. This also applies to cases when a work originally published as a journal article was later included in a book as a chapter.


As a first comment, since all the references you are talking about are before 1970, there is a (high) chance that they will not be available (easily), so accessibility is probably a problem that you will encounter yourself (let alone your readers).

On the other hand, I would say that a reference is supposed to show the progress in a specific field. So (and if I didn't misunderstand something in your question), I would rather have the article that describes the finding you are referring to (e.g. the first application of a method, the discovery of an enzyme or the first description of a microorganism) rather than a later article citing that first one.

Of course, if the later article reports a development in the method that is interesting for your narrative, you could also add that to show the progress.

I don't understand completely why in some cases you cannot determine precedence - maybe I miss something. But in general, for reviews or original research articles, I try to find a reference that is the first occurence, rather than someone else using that method. I remember once trying to find the first describing a microorganism and I went back to 1957, which was citing an even older article which I couldn't find it. I reported it as the first accessible report on this microorganism and used the article from 1957.

So, in summary, I think you should go as back as you can get relatively easily access to old papers, and as close as possible to the article whose results are depicted in the text you cite.

If a part of the text is described without proper citation and you evaluate it as an opinion, rather than a finding, I think I would try to describe it in the review as such and/or cite those that actually proved it (probably later).

I hope I didn't misunderstand the question and you wanted something else...

In response to the edit: That seems like a quite different story from what I initially thought. I also now assume that the authors are the same (or overlapping), since you mention the text being copied verbatim (a bad practise if you ask me when writing a book chapter based on an article - but that was not the internet era). So there it is... I accidentally answered part of the question. I think it would be more common to have an article out first before writing a book chapter (assuming the editor sees the article first and then invites the authors to write a book chapter). But nevertheless, considering the intellectual property belongs to the same authors, and also the maturity (of age) of these works, I could choose to cite the one that is available more easily, i.e. available online or in a newer edition of the book.

There is no use for double citations on a finding that is proven once experimentally but described twice by the same authors. But if none of the authors is the same in the two sources, and it's still verbatim, then it seems like a case of plagiarism. I would still assume the article --> book direction, but I don't think the other way around could not work either.

  • Thank you for your answer! Indeed, finding some of these references has been a challenge. I have edited the question to hopefully clarify some of these points. To be clear, the references in question are identical (same author(s), same content), differing only in where they were published. The ones where precedence cannot be determined do not cite each other (through a statement or otherwise), hence the difficulty.
    – Guho
    Dec 5, 2016 at 23:38
  • I saw your comment after the edit, but I think what I wrote covers what you ask. :)
    – BioGeo
    Dec 5, 2016 at 23:56

I would cite the one which has got maximum citations. This would improve the probability of the reviewer having read it already. Also it would mean that this one is more easily accessible or available. If you are not sure, it is probably because there is something important in each paper. Then cite both!


I work in mathematics, where literature references are usually given in detail only in the bibliography at the end; in the main text of the paper, there would be just short pointers (like "Einstein [3]" or "[Ein1905]") to the bibliography. In your situation, with identical text published in several places, I'd list all those places in a single bibliography entry. I'd start with the first (as far as I can determine) publication and then continue with "reprinted in ..." for each of the republications. In the main text, I'd just have a pointer to that bibliography entry; there's no need to mention the multiple publications in the text.


I have reviewed recently reviewed a paper that had this passage:

In this paper, we show the algorithm to compute X. Very similar algorithms were simultaneously published by Alice, Bob and Charlie [5,6,7]. The same result being published by various important researchers, in our opinion, strengthens the significance of this result. However, our work differs from them ...

I think this is perfectly fine. Actually, I am convinced that the authors did a perfectly fine literature review -- even enough to know the brand new publications, and have no purpose to "sneak their manuscript into the conference."

That being said, I think it is perfectly fine (and most proper way) to write a sentence like following.

This result was simultaneously published by a number of scientists [2,3,4,5,6]. In this paper, we improve the mentioned result and ...

Actually, in my opinion, it would not be proper to refer only one or two since the reviewer might be very familiar with one of them and question the paper's sufficiency in terms of literature review.

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