Search for books using Washington University Libraries' catalog.
Just want to browse? Library of Congress Classification Outline
But remember, browsing stacks misses ebooks, books at other locations and books that are checked out.
When you search in most catalogs, you are searching titles, authors, subject headings and sometimes chapter titles. When you use Google Book search, you are searching the entire contents of books. I often find this useful for specific phrases, techniques, etc. Once you identify a book that has useful information, you then will often want to go to a catalog to find out where/if we have it at WU. Google Books won't actually let you read more than a few pages in most cases. But it can be really good in leading you to books that you wouldn't have found in the catalog.
Also, don't forget that the "References" lists in books will often lead you to journal articles and vice versa.