- Understanding Vibrato:Vocal Principles that Encourage Development, by David L.Jones at VoiceTeacher.com
- Making and hearing the vocal trill: An acoustical study. (A) J. Acoust. Soc. Am. Volume 91, Issue 4, pp. 2434-2434 (April 1992) Issue Date: April 1992
- The Trill - Neil Howett Article
- Vocal Extended Technique entry at Wikipedia
- Speed Up Your Trills
- The Vocal Trill
- Music Educators Journal, Vol. 29, No. 3 (Jan., 1943), p. 40
(article consists of 1 page) - Published by: MENC: The National Association for Music Education
- Stable URL: http://www.jstor.org/stable/3386269
Maria Callas discusses ornamentation in vocal music.