Try these first...

  RILM Abstracts of Music Literature  [more info]
Indexes international scholarly literature on music 1969-present.

  International Index to Music Periodicals (IIMP)  [more info]
Indexes more than 400 scholarly and popular music periodicals, with an emphasis on recent issues.

  JSTOR (full database) or JSTOR: Browse Music Titles  [more info]
The music journals include full-text for 35 scholarly music periodicals that are core to the profession.

  Music Index  [more info]
Indexes more than 640 international scholarly and popular journals and magazines.  Best source for popular music.

Try also...

  International Index to the Performing Arts (IIPA) [more info]
Indexes more than 200 scholarly and popular performing arts periodicals and covers nearly all aspects of the world of performing arts, including film, theater, opera, and dance. 1998-present.

  RIPM: Retrospective Index to Music Periodicals (1800-1950)  [more info]
Indexes and provides detailed contents descriptions for 51 periodicals from 15 countries. Late-18th through mid-20th century coverage.