You can browse titles by subject category or see a full alphabetical list of titles.  Both options are available from the Gale Books homepage.  

After clicking on either a subject category or the full title list link, click on any title for more information.  Clicking on any ebook will bring you to an informational page that includes information about the publication, a table of contents, and a book index. For multivolume works, use the "Choose a Volume" dropdown menu to select sections beyond those listed by default. In select instances, you may be asked to select a volume first.  

The Book Index section allows you to browse the publication's entries alphabetically, just like you can with a physical copy of a book.