1. The role of learning phenomena in the ontogeny of exploration and play. pp. 343-406 in Primate Bio-Social Development: Biological, Social and Ecological Determinants. eds., New York, Garland, 1977.
2. Investigate behaviour. Pp. 463-493 in Behaviour of Non-Human Primates, vol. 2. eds., New York and London, Academic Press, 1965.
3. Behavioral effects of a change in the physical environment: A pilot study of captive chimpanzees
4. Strangers in a strange land: Abnormal behaviors or abnormal environments? pp. 1-28 in Captivity and Behavior. eds., New York, Van Nostrand Reinhold, 1979.
5. Chimpanzees of the Gombe Stream Reserve, pp. 452-473 in Primate Behaviour. ed., New York, Holt, Rhinehart and Winston, 1965.