1. WALLIS BUDGE, The Paradise of the Fathers.
2. HAVELOCK ELLIS, Studies in the Psychology of Sex, Vol. VI.
3. FREUD, “Civilized Sexual Morality and Modern Nervousness,” Collected Papers, Vol. II.
4. K. B. DAVIS, Factors in the Sex-Life of Twenty-two Hundred Women.
5. MAYO FOUNDATION LECTURES, 1923–4, Our Present Knowledge of Heredity.