Handbuch der Oper is in my opinion one of the books every single singer should have. It is kind of a Bible for Opera Singers concerning the amount of information about the major Operas composed in the History of Music.
It is organized by Composer’s name and then Opera’s title in alphabetic structure. In each opera there’s a complete section which approaches the voice type of each role and its peculiarities. For example, where the action takes place, details about the choir or eventual ballet participation. There’s also a section about the story, stylistic issues and also contextualization about the text and its historic background.
The appendix is extremely helpful and I do love this book. It has more than 900 pages of useful information. An amazing work by R. Kloiber, w. Konold and R. Maschka edited by Bärenreiter.
by Marina Pacheco