H. S. Curtis: "Automatic Movements of the Larynx," Amer. Jour. Psych., Vol. 11, p. 237. 1900.

H. L. F. Helmholtz: Die Lehre von den Tonempfindungen. Braunschweig, 1862.

E. W. Scripture: The New Psychology, London, 1897.

The Elements of Experimental Phonetics. New York, 1902.

The Study of Speech Curves. Washington, 1906.

William James: The Principles of Psychology. New York, 1890.

Hansen and Lehmann: "Ueber unwillkuerliches Fluestern," Philo. Stud., Vol. 11, p. 471. 1895.

C. Lloyd Morgan: An Introduction to Comparative Psychology. 1894.

Wilhelm Wundt: Grundzuege der physiologischen Psychologie. Leipzig, 1874.

Grove's Dictionary of Music and Musicians.