1. Increasing vocal effectiveness;Raphael,1997
2. The role of the acting-voice trainer in medical care of professional voice users;Freed,1997
3. Twelve crucial minutes;Phillips;Teach Music,1994
4. Choral warmups: preparation to sing, listen and learn;Stegman;Music Educ J,2003
5. What happens during vocal warmup?;Elliot;J Voice,1995