Books often provide more detail and are more expansive than academic articles. Sometimes they are collections of papers or essays that are essentially what you would find as an academic article.
Library Search is the main tool for books in the Temple University Libraries system. The system uses the Library of Congress classification system, which uses letters and numbers to arrange books. Political Science is generally in the area of the call letters J, law is K, and country and state topics are generally in the range D-E-F. .
If you can't find a title or all the available copies are checked out, try E-ZBorrow, or ILLiad. These are tools for searching and requesting books you know the title of from academic libraries. The service can usually deliver a book that is available in about 4-5 days.