There are lots of ways to come across potentially useful books. But the last thing most people want to do is to buy every book they need for every project they do.
All you need is enough information to use one of the access points in your library catalog and you can find and borrow your book.
Get as much information from your professor (or other source) as you can - especially: title, author and publication date. Then go to the catalog link on the library homepage and find your book.
Tip: if your library doesn't have your book, ask a librarian to help you get it from another library.