Orangutans
1971 Pongo pygmaeus. Mammalian Species No. 4:1-6.
1985 (with L.B. Holthuis). The Nomenclature of the Orang Utan. Zoo. Meded. Leiden 59:411-7.
1986 Systematics of the Great Apes. Comparative Primate Biology 1:187-21
1987 Monkey Business with Red Apes. J. Hum. Evol. 16:537-542.
1989 Brief Communication: Weights of Wild Orang Utans. Amer.J.Phys.Anthrop. 81:1-3.
2001 Primate Taxonomy. Washington: Smithsonian Institution Press.