Books are the bridge between your textbook and scholarly journal articles. They are usually your best resource for "the basics" -- an introduction, overview, and history of your topic. The quickest way to find books is to search the library's book databases:
Another way to find books is to "browse" -- go to the library's shelves and take a look.
At Penn State Harrisburg Library, we use the Library of Congress call number system to shelve our books:
For more details, see the Library of Congress Classification Outline.
If Penn State doesn't have the books you want, there are additional resources: