If you have a mentor already, the best way to get started with your library research is to get a paper or two, or a research proposal from your mentor. If the paper is very recent, you can do a really good job of obtaining the beginning of a bibliography by examining the references in that paper, particularly the references to aspects that you will be following on. When you get those references, you can check their references, and so on.
The Columbia Library system has a great web presence that
makes searches much easier and also allows you to go into more
recent papers than the key papers obtained from your mentors.
The Clio
catalogue is very useful for finding books that cover your
subject.
There is wide range of literature databases that this website gives you access to.
As you will see there is a myriad of choices in this section, and you should spend some time exploring in the context of your project. The tool that I find the most efficient for searches is the Web of Science. Google scholar is becoming more useful and finds a similar set of articles and now recognizes your CU affliation and links to the full text. However, it has fewer options than the Web of Science.
After finding articles of interest, look at the references cited
(going backward in time) and the papers that cite the paper (going
forward in time). The Elink feature allows you to access the
article directly.