Dizionario enciclopedico dell'opera lirica /

by Rosenthal, Harold D.
Firenze : Le Lettere, 1991

German opera : from the beginnings to Wagner /

by Warrack, John, 1928-
Cambridge ; New York : Cambridge University Press, 2001

Concise Oxford Dictionary of opera,

by Rosenthal, Harold D., Warrack, John, 1928-
London, New York, Oxford University Press, 1964