Is it bad practice to cite MSc dissertations? While searching for references on a certain class of problems I came across a well-written master's dissertation. It did not contain much in terms of new results, but  it did a good job of explaining what happens in the important papers in the field (or so I believe). This was helpful - my interest in that class of problems is that it's adjecent to the problem I'm writting about, so it's important for me for context and historical reasons, but it's not a subject I want to research in much depth; having read the dissertation and a introductions to some of the relevant papers, I feel I know as much as I need to know. I should also mention that some of the relevant papers are in French, so I was very grateful that someone explained in English what their gist is. I also feel that what I read in the published papers is enough to reasonably write all that I need to write in the introduction, but having looked through the dissertaition certainly helped me orient myself.

Now, my dillema is: Should I cite the dissertation? It is not generally seen as a requirement to cite expository materials on a subject, so I don't think I have to. But I also feel that it would perhaps be nice to cite it: it acknowledges that I benefited from reading it, and it helps potential readers who might become interested in the subject. If it was a published survey article, I would definitely cite it. On the other hand, this is a piece of writting that didn't go through the usual peer review process, and that was almost by definiton written by a rather inexperienced mathematician. I'm worried including the citation could annoy some readers, and possibly the dissertaion's authour.

What is the best course of action in a case like this?
Cite it. It's a source you used, so you need to cite. 

In addition, good explanations are also good for readers who are looking for an introduction.




  didn't go through the usual peer review process 


Where I am, a Master thesis is reviewed (+ graded) by two professors, and that can include a list of required corrections/clarification for the final version. A paper is possibly reviewed by 2 PhD students who have barely published their first paper...


  was almost by definiton written by a rather inexperienced mathematician


so is everyones first paper. Including possibly reviews: I know PhD students who were put to the task of writing a review paper right with their literature study to familiarize them with their thesis subject.



There are things in my Diplom thesis that I wouldn't write or do like that any more (now, 15 years later: science and my personal knowledge have advanced, after all - which is as it should be), though the downright mistakes I've found are mostly typos or otherwise the correct expression is clear. So it's rather that I have different expressions/sentences/wording now that I think are more clear/better or explain things I could only observe back then.
But then, the same is true for some of my (peer-reviewed) papers.