• Allen, C. & Bekoff, M. (1996). Intentionality, social play, and definition
• Athey, I. (1984). Contributions of play to development.
• Beach, F. A. (1945/1971). Current conceptions of play in animals.
• Bekoff, M. (1978). Structure, function, and the evolution of a cooperative social behavior.
• Bekoff, M. (1999). Social cognition: Exchanging and sharing information on the run.
• Bekoff, M. (2000). The essential joys of play.
• Bekoff, M. (in press). Social play behaivor: Cooperation, fairness, trust, and the evolution of morality.
• Bekoff, M. & Allen, C. (1998). Intentional communication and social play
• Biben, M. (1998). Squirrel monkey playfighting: Making the case for a cognitive training function of play.
• Boulton, M. J. & Smith, P. K. (1992). The social nature of play fighting and play chasing
• Byers J. A. & Walker, C. (1995). Refining the motor training hypothesis for the evolution of play.
• Clarke, L. J. (1999). Development reflected in chase games.
• Eibl-Eibesfeldt, I. (1989). Human ethology.
• Fagan, R. (1975). Modelling how and why play works.
• Fagan, R. (1981). Animal play behavior.
• Fagan, R. (1984). Play and behavioral flexibility.
• Fein, G. G. (1984). The self-building potential of pretend play or "I got a fish, all by myself".
• Fortes, M. (1938). Social and psychological aspects of education in Taleland.
• Garvey, C. (1990). Play.
• Gilmore, J. B. (1966/1971). Play: A special behavior.
• Haight, W. L. & Miller, P. J. (1993). Pretending at home: Early development in a sociocultural context.
• Herron, R. E. & Sutton-Smith, B. (Eds.) (1971). Child's Play.
• Howes, C.; Unger, O.; & Matheson, C. (1992). The collaborative construction of pretend: Social pretend play functions.
• Myers, D. (1998). Playing against the self: Representation and evolution.
• Nabhan, G. P. & Trimble, S. (1994). The geography of childhood: Why children need wild places.
• Pellegrini, A. D. & Smith, P. K. (1998). Physical activity play: The nature and function of a neglected aspect of play.
• Rosenberg, A. (1996). Is there an evolutionary biology of play?
• Sutton-Smith, B. (1999). Evolving a consilience of play definitions: Playfully.
• Sutton-Smith, B. & Kelly-Byrne, D. (1984). The phenomenon of bipolarity in play theories.
• Symons, D. (1978). Play and aggression: A study of rhesus monkeys.
• Tomasello, M. (1999). The cultural origins of human cognition.
• Vandenberg, B. R. (1986). Beyond the ethology of play.
• Wolf, D. P. (1984). Repertoire, Style, and format: Notions worth borrowing from children's play.

Animal Comparative Data:

• Bottlenose dolphins: from DeLong, T.C. (1999). Observations of free-play behavior in captive juvenile Bottlenose Dolphins (Tursiops truncatus). In Reifel, S. (Ed.) Play and culture studies, Vol. 2. C. T.: Ablex Publishing Co.
• Black-tailed deer -- play tag with role reversals (Miller, 1975)
• Lions -- capture, some R&T, role reversal (Schaller, 1972)
• Chimps -- Lawick-Goodall (1968)
• Rhesus monkeys -- Symons (1978)
• Wild house mice -- Wolff (1981)
• African ground squirrel -- Ewer (1966)
• Patas monkeys -- Dolhinow (1971)
  

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