1. Narasimhan, R., Modelling Language Behaviour (Springer-Verlag, Berlin, 1981).
2. Wells, Gordon, Learning through interaction: The study of language development (Cambridge University Press, Cambridge, UK, 1981), p.86f.
3. Piaget, Jean, “The Psychogenesis of Knowledge and Its Epistemological Significance”, in M. Piatelli-Palmarini, ed., Language and Learning: The Debate between Jean Piaget and Noam Chomsky (Routledge and Kegan Paul, 1979), p.23f.
4. Piaget, Jean, “Language within Cognition”, in M. Piatelli-Palmarini, ed., Language and Learning: The Debate between Jean Piaget and Noam Chomsky (Routledge and Kegan Paul, 1979), p.164f.
5. Op. cit., p.165.