Oxford Music Online is a gateway to Grove Music Online (which includes the full texts of The New Grove Dictionary of Music and Musicians, The New Grove Dictionary of Opera, and The New Grove Dictionary of Jazz); The Oxford Companion to Music (which offers more than 8,000 articles on composers, performers, conductors, individual works, instruments and notation, forms and genres); and The Oxford Dictionary of Music (which supplements Grove’s more extensive coverage with content geared toward undergraduates and general users).
Notice that you can choose to search only biographies from the main page. You can search all 3 resources at once or choose to search the resources individually. The result list will tell you which resources are providing the results.
Grove Music Online will give the lengthiest article and will provide a complete list of the composer's works. The Oxford Companion and The Oxford Dictionary will contain shorter articles.
The Garland Encyclopedia of World Music is devoted to the music of all the world's peoples, organized geographically, with each volume devoted to a single region and coverage assigned to the world's experts on specific music cultures.
Baker's Biographical Dictionary of Musicians c 2001 Reference f ML105 .B16 2001 (6 volumes)
Garland Encyclopedia of World Music f ML100 .G16 199 (10 volumes)
New Grove Dictionary of Music and Musicians Reference ML100 .N48 2001 (29 volumes)
The Oxford Companion to Music. Reference ML100 .O92 2002
The Oxford Dictionary of Music Reference ML100 .K35 2006