These books are reference books. A reference book is a book that is used primarily to supply background information on a particular topic. They are often produced by experts in a particular field and are not intended to be read from cover-to-cover: instead, you can find an entry in the reference book that mentions your topic and just read that entry. Most reference books will have an index in the back of the book that will allow you find out on which page your topic would be.
Examples of reference books include dictionaries, encyclopedias, almanacs, and handbooks.
Reference books are found in the Reference Collection, or the green-labeled shelves in the library. You cannot check out reference books from the library, but you can look at them for as long as you are in the library, and you may take photo-copies of reference books.