1. Primate tool behavior;Beck,1975
2. Sex differences in the use of natural hammers by wild chimpanzees: A preliminary report;Boesch;Journal of Human Evolution,1981
3. The ontogeny of primate intelligence and its implications for communicative potential: A preliminary report;Chevalier-Skolnikoff,1976
4. A Piagetian model for describing and comparing socialization in monkey, ape, and human infants;Chevalier-Skolnikoff,1977