Tomasello, M. (2003) On the different origins of symbols and grammar. In M.H. Christiansen and S. Kirby, editors, Language Evolution: The States of the Art . Oxford University Press.

Tomasello, M. (2003) On the different origins of symbols and grammar. In M.H. Christiansen and S. Kirby, editors, Language Evolution: The States of the Art. Oxford University Press.

2003	-	Language Evolution: Consensus and Controversies - Christiansen,Kirby	::	8
2005	-	The Evolution of Language: A Comparative Review - Fitch	::