1. " A Guide to Mental Testing;Cattell, R.B.,1936
2. Clark, L. P. (1914). Amer. J. med. Sci., 148, 729 (1918). J. Amer. med. Ass., 70, 357.
3. Clark, L. P. (1918). Amer. J. med. Sci., 155, 796.
4. Clark, L. P., and Cushing, K. (1931). Med. J. Rec., 133, 27.
5. Crown, S. (1947). J. Personality, 16, 198.