1. (1985) Family group systematics and evolution among catarrhine primates. In (ed.): Ancestors: The Hard Evidence. New York: Alan R. Liss, Inc., pp. 14-22.
2. (1986) Molecular evidence for catarrhine evolution. In , and (eds.): Major Topics in Primate and Human Evolution. Cambridge: Cambridge University Press, pp. 107-129.
3. The relationships of Sivapithecus and Ramapithecus and the evolution of the orang-utan
4. Hominoid primates from a new Miocene locality named Meswa Bridge in Kenya