1. Trends in musical theatre voice: An analysis of audition requirements for singers;Green;J. Voice,2014
2. Estill voice trainig Level One Workbook: Figures for Voice Control;Estill,2019
3. J. Estill, M. McDonald Klimek, K. Obert, K.M. Steinhauer, Level Two Workbook: Figure Combinations for Six Voice Qualities, 2nd ed., Estill Voice International, 2019.
4. The Estill Voice Model: Theory & Translation;Steinhauer,2017
5. Certification Manual Version 5.1;Campone,2019