Books in our libraries are shelved by the LC (Library of Congress) classification system. In the main library, books with call numbers starting with the letters A-D are located on the second floor of the library, while books with call numbers starting with the letters E-Z are located on the third floor of the library.
If a book is marked as a government document, it will be on the second floor.
To find books (and more!) use DePauw's Discovery search. It will also search materials owned by libraries all over the world.