We use the Library of Congress classification system, which is the system most academic libraries use. LC classification uses letters and numbers to designate where the books are shelved. So, for the first book listed in box on the left, the call number is KF9619. N4 2008.
First, look at the end of the shelf ranges to find the KF section, then look for the 9,000s, and then find 619.
The next part of the call number is the Cutter number, and Cutters are arranged alphabetically, then in decimal order. Find the Ns, then find the N4s.
Your book should be there!
Don't judge a book by its cover isn't just a cliche, it's good advice. Anyone can write and publish a book. You still need to think about what you're reading and be critical. For example, a book about Scientology by the founder L. Ron Hubbard is going to be very different from a book written by a former adherent of Scientology, or one written by a professor of theology. All three are valid sources, but you must decide which is the best to cite for the point you are trying to make.