1. Schein, M.W. & Hafez, E.S.E. The physical environment and behavior. in The Behaviour of Domestic Animals 2nd edn. (ed. Hafez, E.S.E.) 65–84 (Williams & Wilkins, Baltimore, 1969).
2. Kaumanns, W. General aspects of primate keeping and colony management. Primate Report 49, 47–53 (1997).
3. Novak, M.A., O'Neill, P. & Suomi, S.J. Adjustments and adaptations to indoor and outdoor environments: Continuity and change in young adult rhesus monkeys. Am. J. Primatol. 28, 125–138 (1992).
4. Bryant, C.E., Rupniak, N.M.J. & Iversen, S.D. Effects of different environmental enrichment devices on cage stereotypies and autoagression in captive cynomolgus monkeys. J. Med. Primatol. 17, 257–269 (1988).
5. Erwin, J. & Deni, R. Strangers in a strange land: abnormal behaviors or abnormal environments. in Captivity and Behavior: Primates in Breeding Colonies, Laboratories, and Zoos. (eds. Erwin, J., Maple, T. & Mitchell, G.) 1–28 (Van Nostrand Reinhold, New York, 1979).