Reference sources provide factual or essential background information.
A good starting point: Music Online Reference.
Music Online: Reference is a collection of over 169 e-book resources focusing on African-American, classical, and world music.
Next source to check: Oxford Music Online.
Supplement these e-references with print reference, found in Bishop Library, and listed in the center box.
Image Source: Koobak. CC BY-SA 3.0. Wikimedia Commons.
ALL of the reference resources below are found in either Music Online Reference or Oxford Music Online.