1. Ackermann, R.R., 1998. A quantitative assessment of variability in the australopithecine, human, chimpanzee, and gorilla face. Ph.D. Thesis. Washington University, St Louis.
2. Using extant morphological variation to understand fossil relationships: a cautionary tale;Ackermann;S. Afri. J. Sci.,2003
3. Ontogenetic integration of the hominoid face;Ackermann;J. Hum. Evol.,2005
4. Variation in Neandertals: a response to Harvati (2003);Ackermann;J. Hum. Evol.,2005
5. Craniofacial variation and developmental divergence in primate and human evolution;Ackermann,2007