Oxford Music Online

The Oxford Music Online (OMO) portal offers full-text access to Grove Music Online (GMO).
The music encyclopedia GMO is regularly updated and offers 50,000 articles on musicology and over 30,000 biographical articles including a list of works on composers and artists, with links to audio files with music examples, additional illustrations and related pages from other providers on the Internet (portraits of composers, music publishers, record labels, orchestras, etc.). In addition to a chronological list of Congress Reports (1860 ff.), the following music dictionaries are included in full text: The New Grove Dictionary of Music and Musicians , 2nd Edition; The New Grove Dictionary of Jazz, 2nd Edition; The New Grove Dictionary of Opera; The Norton Grove Dictionary of Women Composers; The Grove Dictionary of American Music, 2nd edition; The Grove Dictionary of Musical Instruments, 2nd edtion.
The search can be extended to two OUP reference works, the article redirects to full text on Oxford Reference:

• The Oxford Companion to Music (Revised First Edition):
  more than 8,000 articles on all topics related to music, with - through a number of new entries on topics such as politics, religion, psychology and computers - consideration of their social and cultural context. Also covered are current research and approaches in music, including analysis, theory, ethnomusicology and performance practice.
• The Oxford Dictionary of Music (2nd Edition):
  12,500 articles on all music topics