http://www.oxfordwesternmusic.com

Electronic version of the 6-volume Oxford History of Western Music by
UC-Berkeley musicology professor, Richard Taruskin.   It covers western
music of all eras, with an emphasis on the most studied works of the last
two centuries.  The author situates the music history in the larger social,
cultural, and political context and focuses on how the canon of western
music is formed.  Many articles have direct links to related articles under
“See Also from Grove Music Online” at the bottom of the left sidebar.