1. Teaching Tricky Diphthongs to Your Choir;Tschiggfrie,2015
2. Choir acoustics: an overview of scientific research published to date;Ternström;Int J. Res. Choral Singing,2003
3. Spectrographic Analysis of the Acoustical Properties of Selected Vowels in Choral Sound;Hunt,1970
4. Formant frequencies of choir singers;Ternström;J. Acoust. Soc. Am.,1989
5. Physical and acoustic factors that interact with the singer to produce the choral sound;Ternström;J. Voice,1991