I am not sure how many musicians know about Google books, but it is a very useful tool for musicians and composers alike. I started using it almost two years ago to aid in my musical studies. To put it simply you can search through countless books on composition technique and music theory just like you would a typical Google search. However the results are not always accessible for free. Most books that are still in print have a link that takes you to a purchase page. But here is the secret sauce, part of the Google Books project’s initiative was to scan older books from University libraries in an effort to preserve them and make them digitally available via online search.  Books that are outside the copyright window are available for full download in .pdf format. Read more