The New Grove Dictionary of Opera: 4 volumes

Incorporating a decade of musicological research, the Dictionary is unsurpassed in its scope and quality, with contributions from over 1,300 of the world's leading critics and scholars. A remarkable 11,000 articles, all fully cross-referenced, create a work that has become established as the essential opera reference. Indeed, every aspect of this varied art form is covered: composers, conductors, directors, performers, librettists, literary sources, cities and countries, operatic historians, and opera genres and terminology.
BLOver 1800 operas are discussed from the late 16th century Florentine Camerata, through the great 18th and 19th century operas, to contemporary works such as the minimalist theatre pieces of Philip Glass
BLThe lives and careers of over 2900 composers are discussed in depth, with entries containing critical assessments as well as discussion of their individual careers and major achievements
BLProfiles of every singer who has made a significant contribution to opera are included, from Francesco Rasi in the 1600s to Luciano Pavarotti in the 1990s
BLTwo unrivaled indices of character names and arias make it the most useful and user-friendly opera dictionary available
BLIllustrated throughout with rare photographs, reproductions of original posters, set and costume designs, and scenes from recent performances

Although not for every opera lover (or every opera lover's budget), this massive four-volume set--each volume coming in at around 1,300 pages--is indispensable for the opera educator, writer, or major fanatic. While in any encyclopedia the quality of writing and the critical viewpoint must of necessity be somewhat varied, the standards in the Grove series of reference works are always high and the level of usefulness enormous. Almost any opera that debuted before 1992 is to be found within these pages, making it especially useful in this age of obscure revivals; most singers of any note who had established careers before that date are also included. Although somewhat Anglocentric in its inclusions, this remains an invaluable reference work.