1. The emergence of symbols: Cognition and communication in infancy;Bates,1979
2. The acquisition of performatives prior to speech;Bates;Merrill-Palmer Quarterly,1975
3. Bayley scales of infant development;Bayley,1969
4. The onset of signing in young children;Bonvillian,1990
5. Sign language acquisition: Developmental perspectives;Bonvillian,1993