«What Does It Mean to Be Human?», Smithsonian Museum of Natural History, по состоянию на 27.10.2014, www.humanorigins.si.edu.

Johann De Smedt et al., «Why the Human Brain Is Not an Enlarged Chimpanzee Brain», in Human Characteristics: Evolutionary Perspectives on Human Mind and Kind, ed. H. H0gh-Olesen, J. Tennesvang, P Bertelsen (Newcastle upon Tyne: Cambridge Scholars, 2009), стр. 168–181.