Christy, V. A., & Paton, J. G. (1990). Foundations in singing: A basic textbook in vocal technique and song interpretation (5th ed. medium-low voice ed.). W.C. Brown.
Lua i Stíl Chicago (17ú heag.)Christy, Van Ambrose, agus John Glenn Paton. Foundations in Singing: A Basic Textbook in Vocal Technique and Song Interpretation. 5th ed. medium-low voice ed. Dubuque, Iowa: W.C. Brown, 1990.
Lua MLA (9ú heag.)Christy, Van Ambrose, agus John Glenn Paton. Foundations in Singing: A Basic Textbook in Vocal Technique and Song Interpretation. 5th ed. medium-low voice ed. W.C. Brown, 1990.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.