1. Altmann J., 1974.Observational Study of Behavior: sampling methods. Behaviour, 49: 227–267.
2. Altmann S. A., &Altmann J. 1979.Demographic Constraints on Behavior and Social Organization. In: I.S. Bernstein and E.O. Smith, eds. Primate Ecology and Human Origins: Ecological Influences on Social Organization, pp. 47–63. Garland STPM Press, New York.
3. Blaffer Hrdy S., 1981.“Nepotists” and “altruists”: The behavior of old females among macaque and langur monkeys. In: P.T. Amoss and S. Harell, eds. Other Ways of Growing Old, pp. 59–76. Stanford University Press, Stanford.
4. Dawkins R., 1976.The Selfish Gene. Oxford University Press, Oxford.
5. Dittus W.P.J. 1975.Population Dynamics of the Toque Monkey, Macaca sinica. In: R.H. Tuttle, ed. Socioecology and Psychology of Primates. pp. 125–151. Mouton Publishers, The Hague.