RILM Abstracts of Music Literature. Covers scholarly literature, but also conference papers and essays, dissertations, and music articles in non-music journals. There is no access to the text of articles in RILM, but the UC-Elinksbutton will occasionally lead you to it.
Music Index. No articles online here, but it covers a lot of older journals and magazines you might not find elsewhere. The UC-Elinks button will sometimes lead you to the online article.