Πρωτότυπο: The Clippinger Class-Method of Voice Culture. Edited by Frank Damrosch, W.A.F., Granville Bantock, Heinrich Kiehl, Ebenezer Prout.
Μετάφραση: Η Clippinger Class-Μέθοδος Voice Πολιτισμού. Edited by Frank Damrosch, WAF, Granville Bantock, Henry Kiehl, Ebenezer Prout.