Flute and Beethoven” . Raptus Association for Music Appreciation . http://www.raptusassociation.org/beethmoze.html . Retrieved 2010-09-27. Rosen, Charles (1998). The Classical Style: Haydn, Mozart, Beethoven (2nd ed.). New York : W. W. Norton & Company. ISBN 0393317129 . OCLC 246977555 . http://books.google.com/books?id=aAFUOreO-nMC . Sadie, Stanley , ed (1998). The New Grove Dictionary of Opera