Once you've found a book or article that's relevant to your topic, you can use it to find more that are about the same topic. Do not start by searching in subjects because these are "controlled vocabulary" meaning specific words are used for specific topics and these words are not always intuitive. For example, the subject term for the "Indianapolis 500" is "Indianapolis Speedway Race."
Reverse citation-searching is the complement to citation mining. Take a book or article that is relevant to your topic and see what has cited it after publication. Note that it takes a long time to publish books (multiple years) and months if not years to publish peer-reviewed articles, so this technique doesn't typically work for very recent materials.
For the article referenced in citation mining, click "Cited by" on the results screen for Google Scholar:
The cited by link appears for both books and articles in Google scholar.
Once you've found an article or book that's relevant to your topic (or something your professor has recommended), you can use the bibliography or works cited to find more.
Read the bibliography.
Search for the title and author of the work cited. Google Scholar is great for finding articles. The library catalog is great for finding books.
For example, you might see this citation of an article written by Professor Ann Taylor and President Feller:
Search the citation in Google Scholar (you can typically get good results with only the author(s) name(s) and the title of the article):
Get the result and click the Full Text @ Wabash link.
Not seeing the Full Text @ Wabash link? Check out the Google Scholar page of this guide!
You might see this citation by a book written by Acting Dean of the College Todd McDorman
You can search the library catalog for the book. You will generally get good results with the author(s) name(s) and the title:
And here is the book and its availability from the library: