1. Alles, G. A., and Hawes, R. C. (1940). J. biol. Chem., 133, 375.
2. The Physiological Basis of Medical Practice;Best, C.H.; Taylor, N.B.,1945
3. Cattell, R. B. (1929). Brit. J. Psychol., 19, 357.
4. Description and Measurement of Personality;Cattell, R.B.,1946
5. Personality;Co., World Book; Yonkers-on-Hudson, New York,1950