When you find an item in the catalog that has a Find & Request link, then the book or video is checked out or not in our collection.
If a book you need is not available either through PSU or Summit, you can request it (mostly) for free through Interlibrary Loan (ILL). It can take up to 12 days to receive a book through Interlibrary Loan.
The PSU Library does not order textbooks through Interlibrary Loan.
Here's a list of subjects that might interest you. You might consider using some of them as search terms to see if you get better results.
Subjects in Land Use
Sometimes browsing the library stacks can help you find books you didn't even know you were looking for. The following are good areas to peruse.
Maps of the library are available at the 2nd floor Reference Desk, elevator lobbies, and also online.