1. Handbuch der Stimm- und Sprachheilkunde;Luchsinger,1970
2. Singing. The mechanism and the technique;Vennard,1967
3. On vocal registers;Hollien;J Phonetics,1974
4. A review of vocal registers;Hollien,1983
5. The male operatic head register versus falsetto;Large;Folia Phoniatr,1972