Music Index began publishing in 1949. It indexes only periodicals. There is an English-language slant but it does index many foreign titles. The online version covers 1973 on and about eight hundred titles in all. There are no abstracts but there are fairly thorough (if not always consistent) subject headings. Jones Library also has the print volumes from 1949 through 1998.
In addition to feature articles, Music Index does a respectable (but not consistently excellent) job of indexing smaller items such as reviews, columns, and editorials. Although Music Index Online does not itself contain any full text, many citations are linked to full text found in other databases such as JSTOR, Academic Search Complete, Lexis/Nexis, and the Electronic Journal Center. Some of these links are obvious and direct, but some are more hidden. Look for links that refer to LinkSource, which should (theoretically) find full text in any of B-W's databases. For (almost) definitive information on which periodicals BW owns, use the A to Z journal finder system.