Your first source for both physical and and electronic books is the Cook Library Catalog. If you really want a book, but cannot find it at Towson, consider looking for it in the USMAI system or ordering it through inter-library loan using WorldCat. Chat or email a librarian if you are having trouble.
Like most academic libraries Cook library uses the Library of Congress cataloguing system. That means that books or scores are grouped together by topic. If you go to where these items are located on the shelf you will probably find other related books.