1. Trivers, R. L., in Sexual Selection and the Descent of Man (edit. by B. Campbell) (Aldine, Chicago, 1972).
2. Trivers, R. L., Am. Zool., 14, 249–264 (1974).
3. Trivers, R. L., and Hare, H., Science, 191, 249–263 (1976).
4. Wilson, E. O., Sociobiology: the New Synthesis (Harvard, 1975).
5. Hamilton, W. D., J. theor. Biol., 7, 1–52 (1964).