Kay, R. F., & Delson, E. (2000). Oligopithecidae. In E. Delson, I. Tattersall, J. A. VanCouvering, & A. Brooks (Eds.), Encyclopedia of Evolution and Prehistory, 2nd Edition (pp. 490–493). New York: Garland Pub. Co.

Kay, R. F., and E. Delson. “Oligopithecidae.” In Encyclopedia of Evolution and Prehistory, 2nd Edition, edited by E. Delson, I. Tattersall, J. A. VanCouvering, and A. Brooks, 490–93. New York: Garland Pub. Co., 2000.

Kay RF, Delson E. Oligopithecidae. In: Delson E, Tattersall I, VanCouvering JA, Brooks A, editors. Encyclopedia of Evolution and Prehistory, 2nd Edition. New York: Garland Pub. Co.; 2000. p. 490–3.

Kay, R. F., and E. Delson. “Oligopithecidae.” Encyclopedia of Evolution and Prehistory, 2nd Edition, edited by E. Delson et al., Garland Pub. Co., 2000, pp. 490–93.

Kay RF, Delson E. Oligopithecidae. In: Delson E, Tattersall I, VanCouvering JA, Brooks A, editors. Encyclopedia of Evolution and Prehistory, 2nd Edition. New York: Garland Pub. Co.; 2000. p. 490–493.