Kohler, K. J. (1998) The development of sound systems in human language. In Hurford, J. R. and Studdert-Kennedy, M. and Knight C., editors, Approaches to the Evolution of Language: Social and Cognitive Bases . Cambridge: Cambridge University Press.

Kohler, K. J. (1998) The development of sound systems in human language. In Hurford, J. R. and Studdert-Kennedy, M. and Knight C., editors, Approaches to the Evolution of Language: Social and Cognitive Bases. Cambridge: Cambridge University Press.

Studdert-Kennedy,Goldstein, Launching language: The gestural origin of discrete infinity, 2003	::	5
Thomforde, Secret Agents: Synthetic Approaches to Language Evolution, 2004	::