1. Hrdy, S. B. Ethol. Sociobiol. 1, 13–40 (1979).
2. Chapman & Hausfater, G. Behavl Ecol. Sociobiol. 5, 227–240 (1979).
3. Hrdy, S. B. The Langurs of Abu (Harvard University Press, Cambridge, 1977).
4. Sherman, P. W. in Natural Selection and Social Behavior (eds Alexander, R. D. & Tinkle, D. W.) 311–331 (Chiron, New York, 1980).
5. Bertram, B. C. R. J. Zool. 177, 463–482 (1975).