I have looked over the master and PhD thesis of several past colleagues, and it seems that their thesis section are all very organized and does not deviate too much from the standard literature. In fact, I was not at all surprised by their selection and could recognize most of them (if their work was similar to mine). One of my colleague's citation mostly contained widely cited papers from well known conferences.

However, I work in the very multidiscipinary field of "theoretical mathematical biology for engineering applications in computer science related fields". So I need results from a wide range of topics.

I have found that I need to cite obscure math references in order to prove my result. On Google, some of these papers have no or 1 citation. This sharply contrasts with the selection of citation from my previous colleague, which makes me a little nervous. I'm sure these mathematicians are famous in their field, but should I keep on digging until I find the (similar) result in a well known textbook?

Further, the text in this area is extremely abundant but no single source contain all the results. This means I have to continuously cite textbooks despite already citing prominent ones such as Winfree's "Geometry of Biological time".

All in all I will probably have over 80 citations. Is this too much?

There seems to be no guideline or rule to selecting citations. Can people working in engineering, physics, and math provide some insights on how to select/filter the list of citations for a master or PhD thesis?

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    I'd say you're overthinking this. Cite the sources that are important or relevant to your work. Nobody cares how many that turns out to be. Jan 15, 2017 at 3:51
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    Did you use them? Are they helpful? Do you delegate information to them that you do not want to mention in the thesis itself? Having few citations is not a reason not to quote a paper. In fact, what does it matter. Some people are unlucky to not have a very visible publication record, while doing good work. Jan 16, 2017 at 8:54
  • If part of the issue is that you're stretching into fields where neither you nor your advisor have much familiarity with the literature, you might want to sit down with one or more of your institution's subject librarians. They're likely to have a good grasp on some of the interdisciplinary research issues.
    – 1006a
    Jan 17, 2017 at 11:35

1 Answer 1


The general answer to all your questions is to ask your thesis advisor. (S)he will definitely be able to tell you what the customs for theses in your field, and in your university, are.

That being said, I had the impression that you may have some misconceptions about why, and how, we use citations in academic texts. Specifically, you claim that:

There seems to be no guideline or rule to selecting citations.

I would argue that this is because one does not "select" citations as such. Rather, the literature that your thesis cites should emerge from the text you are writing. You build a scientific argument and then, at the appropriate points in the text, refer back the original text whenever you use a pre-existing piece of knowledge. Sometimes this pre-existing knowledge may be standard enough that a textbook is a good source, but it is not uncommon that you will need to refer to original research papers.

If those papers have been cited often or rarely so far is not the right question to ask. Instead, if your argument requires that X is true, you find the original paper that proves X. You don't cite a different paper that also somehow uses X because it is more often cited. If you are not aware of any research that actually showed X, you have a different problem - why can you reliably assume X to be the case in your thesis anyway? Your current approach of writing down results and then worrying about what to cite for them seems a little backwards to me.

All in all I will probably have over 80 citations. Is this too much?

"How many references should I have?" is really the wrong question to ask. You use as many as you need. That being said, if you have very few citations of previous work in a thesis it is usually a bit worrying, as a lack of citations often indicates that a student is not aware of the scientific state of the art or, even worse, of good citation practices. Conversely, citing many previous works is not usually a problem for theses. Of course some upper bounds exist in practice, but 80 citations seems nowhere close to excessive even for a master's thesis. Note that mathematical texts tend to have fewer citations than other STEM fields, so this may have biased your expectations when looking through the literature.

  • "Your current approach of writing down results and then worrying about what to cite for them seems a little backwards to me." - for what it's worth, in some fields "close to practice", this is somewhat common. A certain part of the information one builds upon comes from one's experience with practically used products. And even though certain features might be common or at least present in one or more of these products, it can be hard to find any written proof for that, let alone in a scientific text. Jan 16, 2017 at 11:40
  • @O.R.Mapper I conduct research in software engineering, I know what you mean. However, I still think it's an anti-pattern that we should discourage students from using.
    – xLeitix
    Jan 17, 2017 at 18:15

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