This list contains electronic resources. Below it is a list of reference books that can be found in the library.
Encyclopedias and dictionaries are really good places to start, especially if you are just beginning a project and want to gain and overview of your topic and put it in context. Many encyclopedias have excellent bibliographies that are also helpful to get you started.
These resources can be found in the Reference section of Thrift Library; some are available electronically.
The New Grove dictionary of music and musicians by
This is also available electronically.
From the Library Journal's review:
Now appearing in print and online simultaneously, this expanded second edition of the most substantial, comprehensive music encyclopedia in English deserves applause for including greater coverage of world and popular music, nearly 2000 more articles on 20th-century composers, and more than 29,000 entries (many rewritten or revised) by over 6000 contributors nearly 7000 more entries by 3600 more contributors than graced the 20-volume 1980 edition. New articles on intellectual trends (e.g., deconstruction, modernism, and postmodernism), sociopolitical movements (e.g., feminism, Marxism, and Nazism), and even animal music and sex illuminate music's various contexts far better than did the earlier New Grove's.
The Oxford companion to musical instruments by 
The Garland Encyclopedia of World Music by
From the publisher's site:
The Garland Encyclopedia of World Music is the first comprehensive resource devoted to music research of all the world's peoples. More than 9,000 pages of material, combined with entries by more than 700 expert contributors from all over the world, make this the most complete body of work focused on world music.
Each volume contains an overview of the region, a survey of its musical heritage, traditions and themes; and a description of specific musical genres, practices, and performances. Articles include detailed photographs that show musicians, musical instrument, and the cultural context of dances, rituals, and ceremonies. Other images include drawings, maps, and musical examples for further study.
Baker's Biographical Dictionary of Musicians by
This 6-volume set of Bakers covers all musical genres, with entries written by a distinguished group of area specialists as well as the original articles of Nicolas Slonimsky. More than 15, 000 biographies span the medieval ages to the present.This work continues the tradition of offering the most comprehensive and authoritative information on the musicians, along with interesting and insightful evaluations of their contributions to the musical world. Bakers remains the most affordable, comprehensive and readable of all music reference works, providing everyone from the student to scholar a one-stop resource for all their music biographical needs. Some of the artists featured include: Louis Armstrong Johann Sebastian Bach The Beatles Ludwig van Beethoven James Brown John Cage Maria Callas Johnny Cash Miles Davis Claude Debussy Marvin Gaye Philip Glass George Frideric Handel Charlie Parker Luciano Pavarotti Arturo Toscanini Tom Waits And many more
The Encyclopedia of Popular Music by
First published in 1992, The Encyclopedia of Popular Music is the largest project ever undertaken for the subject. This authoritative biographical encyclopedia of rock, pop, and jazz artists covers popular music from 1900 to the present, including folk, blues, world music, rock, heavy metal, techno, reggae, and hip hop. Edited and largely written by Colin Larkin, it is exhaustive, meticulous, authoritative - and incredibly fun to read. Critically lauded in its previous three editions, the Fourth Edition will not disappoint fans seeking authoritative and reliable information about popular music from around the world. Expanded to ten volumes, the new edition contains 6,000 new entries, and extensive revisions and updates throughout, yielding 50% more material than the 1998 Third Edition. In addition to thousands of biographical entries, this A-Z reference also includes entries covering popular music genres, trends, styles, record lables, venues, and festivals. Key dates, biographies, and further reading are provided for artists covered, along with complete discographies that include record labels, release dates, and a 5-star album rating system. From Grateful Dead to The Killers, from Whitesnake to White Stripes, from R.E.M. to Blink-182, from The Jazz Singer to Jerry Springer - The Opera, and from Bye Bye Birdie to Rent, The Encyclopedia of Popular Music, Fourth Edition has something informative and clever to say about everyone's favorite band.