1. Vibrato and non-vibrato singing: who teaches it? How do they teach it? Does it make a difference?;Nix;Choral J,2013
2. The choir issue, part one;McCoy;J Singing,2011
3. Principles of Voice Production;Titze,1994
4. Some acoustic characteristics of vocal vibrato;Shipp;J Res Singing,1980
5. Caracteristicas acusticas del vibrato en coreutas;Cecconello;Árete,2010