What to do if I can't find references about a listed project of my potential supervisor I am currently preparing for my graduate school application. There is one professor whose research interest in general matches mine. He has listed several potential research projects for prospective postgraduate students and I am particularly very interested in one of them, say Project A. Since Project A's scale is very broad, I planned to read some of his related publications to get familiar with the topic before I contact him via email.

The problem is I can't find any article written by him about Project A on his website or through Google. He did list some selected publications but they all seem to relate to other projects, which are different from Project A. In my view, those projects are more theoretical and related with asymptotic analysis while Project A is related with probability and stochastic modeling. I have not opened all articles to confirm my statement.

Do I overlook anything? Is it possible that a professor lists a project that he has published any related works in the past 3 years? Do it mean the professor don't want to intake students with Project A recently?

I don't want to send a email to the professor and ask for references because I think it's not polite. Currently I am searching the title of Project A and reading related publications by other professors. I have also browsed one of his papers , which is related to another project. What shall I do next? Is it proper to send an email to his current student and ask for reference?
It is completely reasonable and polite to send an email to the professor, saying that you are planning to apply to his department, you were interested by the discussion of Project A on his web page, and asking if he can tell you more about it and/or suggest further reading.