http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
The book also contains brief biographies of composers as well as an index to operas, giving their dates and details of the places at which they were first performed. An invaluable work of refernce, not only for the student and music-lover, but also for the occasional opera-goer.