1. Bateson, W. (1913).Mendel’s Principles of Heredity.
2. Goddard, H. (1916).Feeble Mindedness, its Causes and Consequences.
3. Jennings, H. S. (1930).The Biological Basis of Human Nature.
4. Still, G. F. (1927). “On place-in-family as a factor in diseases.”Lancet, pp. 795 and 853.
5. Clark, R. M. (1929). “The Mongol, a new explanation.”Journ. Ment. Sci. lxxv, 261.