So what is the difference between a reference book and a circulating book?
Reference books are generally housed in a section separate from the circulating collection. They are usually books that offer general background material such as encyclopedias and dictionaries. Other types of reference books could even be atlases and medical source books.
These books are distinguished by the “R” in the call number on the spine of the book and must stay in the library.
Circulating books are anything else in the library that doesn’t qualify to be a reference book. These books are free to checkout and can be recognized by the fact that they don’t have an “R” in the call number.