1. Altmann J (1974) Observational study of behavior: sampling methods. Behaviour 49:227–267
2. Altmann J, Alberts SC (2003a) Variability in reproductive success viewed from a life-history perspective in baboons. Am J Hum Biol 15:401–409
3. Altmann J, Alberts SC (2003b) Intraspecific variability in fertility and offspring survival in a nonhuman primate: behavioral control of ecological and social sources. In: Wachter KW, Bulatao RA (eds) Offspring: human fertility behavior in biodemographic perspective. National Academies Press, Washington DC, pp 140–169
4. Burton FD, Chan LKW (1996) Behavior of mixed species groups of macaques. In: Fa JM, Lindburg DG (eds) Evolution and ecology of macaques societies. Cambridge University Press, Cambridge, pp 389–412
5. Conover WJ (1980) Practical nonparametric statistics, 2nd edn. Wiley, New York, pp 215–226