PRINT REFERENCE SOURCES
A Resource Guide to Themes in Contemporary American Song Lyrics, 1950-1985
The Green Book of Songs by Subject: The Thematic Guide to Popular Music
Oxford Music Online
The most comprehensive online music encyclopedia. See below for sources with more depth of coverage on American music and world music.
Grove Dictionary of American Music, 2nd edition
The largest reference publication on American Music (including Latin America), this second edition provides expanded coverage particularly in the areas of popular music, cities and regions, ethnic and cultural groups, and music technology.
Garland Encyclopedia of World Music
Articles on ethnic and folk music worldwide, describing national and specific musical genres, practices, instruments, performances, and the cultural context.