When looking for books, you'll want to search in the Library Catalog or Scout. When looking for a specific book, the catalog works a bit better. When looking broadly for books on a topic, you'll want to search in Scout, which includes both ebook and print results.
If you need a book we don't have, there are a few options:
WorldCat is the world's largest network of library content and services. WorldCat libraries are dedicated to providing access to their resources on the Web, where most people start their search for information. You can search for popular books, music CDs and videos—all of the physical items you're used to getting from libraries. WorldCat can be used to verify citations, locate an item in another library, or to provide accurate citation information for inter-library loan requests. (Does not include citations to individual articles, stories in periodicals, or book chapters).