A. Hill and S. Ward. Origin of the Hominidae: the record of African large hominoid evolution between 14 My and 4 My. Am. J. Phys. Anthropol., volume 31, issue 9, pages 49-83, 1988.

S. Ward and A. Hill. Pliocene hominid partial mandible from Tabarin, Baringo, Kenya. American Journal of Physical Anthropology, Wiley, volume 72, issue 1, pages 21-37, January 1987.

S. C. Ward, D. C. Johanson, and Y. Coppens. Subocclusal morphology and alveolar process relationships of hominid gnathic elements from the Hadar formation: 1974–1977 collections. American Journal of Physical Anthropology, volume 57, issue 4, pages 605-630, 1982.

S. C. Ward, D. C. Johanson, and Y. Coppens. Subocclusal morphology and alveolar process relationships of hominid gnathic elements from the Hadar formation: 1974-1977 collections. Am. J. Phys. Anthropol., Wiley, volume 57, issue 4, pages 605-630, April 1982.