1. Kinsey, A.C., Pomery, W.B. & Martin, C.E. Sexual Behavior in the Human Male (Saunders, Philadelphia, 1948).
2. Anderson, R.M. & May, R.M. Nature 333, 514–519 (1988).
3. Lanval, M. An Inquiry into the intimate Lives of Women (Cadillac, New York, 1950).
4. Gorer, G. Sex and Marriage in England Today (Nelson, London, 1971).
5. Schofield, M. The Sexual Behaviour of Young People (Longman, London, 1965).