Carstairs-McCarthy, A. (1998) Synonymy avoidance, phonology and the origin of syntax. 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.

Carstairs-McCarthy, A. (1998) Synonymy avoidance, phonology and the origin of syntax. 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.

Fitch, Comparative Vocal Production and the Evolution of Speech: Reinterpreting the Descent of the Larynx, 2002	::	3
Fitch, The Evolution of Language: A Comparative Review, 2005	::	2