Online Resources for Music Scholars
This is an extensive list of online resources in music compiled by librarians at Harvard's Loeb Music Library.
And be sure to check these resources:
The online catalog and digitized content from the British Library.
Early Music Online
A collection of some of the oldest surviving volumes of printed music from the British Library.
The online catalog, including many digitized scores, of the Bibliotheque Nationale de France.
This is an online catalog of holdings of libraries all over the world. It includes a great deal of freely available digital content from the Google Books Project.and Internet Archive. Includes books, scores, audio, video, and websites.
The Wiesbaden Codex
This codex, held by the RheinMain University and Library in Wiesbaden German, contains a significant number of musical and literary works by Hildegard of Bingen.