I'm currently writing my BSc Physics dissertation and I'm using LaTeX with BibTeX so the format of the references is all correct, but there are a number of other papers that I talk about at several points throughout the paper. When referencing one of these papers do I need to include a reference each time I mention it?


Throughout this paper I will adopt values for cosmological parameters obtained by the Planck Collaboration [1].

and later on in the paper...

... there have been numerous projects attempting to measure features of the CMB including the COBE satellite [2], the WMAP [3] and, more recently, the Planck Collaboration ([1]?).

  • 3
    Your department ought to have a preferred citation style, which will give you details for how these citations need to be formatted (for example, some styles license "ibid." and/or "id." for repeated citations under certain circumstances).
    – 1006a
    Mar 28, 2018 at 20:51
  • Not twice in the same paragraph, though. I'm not a physicist but don't go overboard.
    – einpoklum
    Mar 29, 2018 at 13:23
  • @1006a This is something I've already remarked several times elsewhere: many universities or departments around the world don't have style guides or the style guides don't cover such details. See also this meta answer of mine. Said in another way, don't expect there's a policy for everything everywhere. Mar 30, 2018 at 12:27

3 Answers 3


Yes indeed. For several reasons:

  • people might not read your work sequentially, from page 1 to the end;

  • people might forget that there was already a citation somewhere;

  • people don't want to recall all previous citations;

  • the context is different and people don't assume that the reference is the same.

  • 19
    and: While editing, the first reference might be moved or removed.
    – Peter
    Mar 28, 2018 at 0:59
  • 1
    There is no downside to following this advice: it is so easy to include citations with the tools you are using. And if you are worried about distracting the reader: a. don't; b. choose a style of citation eg [23] which offers minimal visual interruption to your text.
    – JeremyC
    Mar 28, 2018 at 8:47
  • 4
    With the reasoning in the first three points, you would also need to put full terminologies instead of their abbreviations throughout the dissertation.
    – Orion
    Mar 28, 2018 at 8:59
  • 2
    A numeric superscript style interrupts the flow of text even less than the square bracket style @JeremyC suggests, and is common in physics (e.g. AIP journals)
    – Chris H
    Mar 28, 2018 at 14:45
  • 1
    @Orion It's much easier to flip (or text-search, or Google) back to the first reference to look up an abbreviation that it is to link two possibly entirely distinct statements to a single reference. Mar 28, 2018 at 18:50

The short answer is yes, for the reasons mentioned by Massimo Ortolano.

How sparsely can you cite? If you're talking about others' work, you should make it clear what work you're talking about at least once a paragraph. E.g.:

The Planck Collaboration ([1]) produced estimates of cosmological constants using lasers and mirrors. The lasers were really cool and allowed them to precisely measure X as equaling pi. Further, Y was e, and Planck's constant was 7.

It also turns out that Z is a complex number, 1+7i. This further implies that our universe is shaped like a donut. The implications go further, suggesting time is periodic. [1]

Having the citation at the end of the paragraph means that every single fact in that paragraph is sourced from that paper. If you are interspersing your own calculations or implications, then you would have to put the citations back at the sentence-by-sentence level.

If your work is in conversation with one main work, then you may have a case for giving them a nickname for that section only, instead of constantly citing them.

In this section that follows, I closely review the 2012 paper by the Planck Consortium [1]; for convenience, I will refer to that work as PC.


PC further found that Z is complex. I question that assumption based on my calculations. If we start with PC's assumption of ..., then necessarily ...


As the others already mentioned: Yes you should. I know, that it sometimes could disturb the reading but as Massimo said, somebody may just read a part and not your whole dissertation and may want to know the citation there.


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