- Travis , L. W. , Bender , W. R. G. and Buchanan , A. R. 1934 . “Research Contributions to Vowel Theory,” . Speech Monographs , I : 65 – 71 .
- Russell , G. O. 1931 . Speech and Voice , Macmillan .
- Metfessel , M. and Tiffin , J. 1921 . “A New Phonoprojectoscope,” . American Journal of Psychology , 41 : 118 – 122 .
- Russell , G. O. 1928 . The Vowel , Columbus : The Ohio State University Press .
- Russell , G. O. 1931 . Speech and Voice , Macmillan .
- Russell , G. O. 1928 . The Vowel , Columbus : The Ohio State University Press .
- Warren , N. 1931 . Laryngeal Action During Speaking. , University of Southern California . M.A. Thesis
Quarterly Journal of Speech
Volume 22, 1936 - Issue 4