You've found your book. Let's say it was Cyberspace Romance. Notice that you've also found something else: the section of the library devoted to dating.
Because call numbers arrange books by subject, books near each other will be about similar topics. Once you find a book on your topic, you may find something even better by browsing the shelves around it.
![[books on shelf]](http://s3.amazonaws.com/libapps/accounts/41838/images/call_number_range.jpg)