The Garland Encyclopedias of World Music. New York: Garland, 1998.
ML100 .G16 1998 MUSIC REFERENCE
The 10 volumes in this series provide in-depth articles on various aspects of world music. Each article provides a bibliography and audio-visual resources. The tenth volume contains a general glossary, a general index, and bibliographic references, discography, and filmography for each geographic area. Each volume comes with an accompanying CD.
Kaufmann, Walter. Selected Musical Terms of Non-Western Cultures: A Notebook- Glossary. Warren, MI: Harmonie Park Press, 1990.
ML108 .K37 1990 MUSIC REFERENCE
This book provides almost 800 pages of terms encountered in world music. Definitions are short and concise. The geographic origin is provided for each term. Each entry refers to one of the 321 literature resources used as a reference.
Musical Instruments of the World: An Illustrated Encyclopedia. Diagram Group. New York: Facts on File, 1976.
ML102 .I5 D5 1976 MUSIC REFERENCE
This book examines instruments by classification (aerophones, idiophones, membranophones, and chordophones). Particular helpful to ethnomusicologist is the chapter entitled "Instruments around the World," which provides illustrations and names of common instruments from the world's geographic areas. This book enables one to see illustrations of instruments that they may hear on world music recordings.
Sadie, Stanley and John Tyrrell (eds). The New Grove Dictionary of Music and Musicians. London: Macmillan Publishers, 2001.
ML100 .N48 2001 MUSIC REFERENCE
Although not specific to ethnomusicology, it containing 1,327 articles on world music, 805 on regional music, countries and cities, New Grove provides excellent bibliographies and general overviews. If researching the music of a specific region, this is a great resource to start with. It is also available online through Arizona State University Library system. The first edition is also available, and includes many articles with somewhat different information and approaches to the topics.