1. Developmental Milestones: Sign Language Acquisition and Motor Development
2. Bonvillian, J.D., Orlansky, M.D. & Novack, L.L. (1983). Developmental milestones: sign acquisition and cognitive development. In D. Rogers & J. A. Sloboda (eds), The Acquisition of Symbolic Skills (pp. 207-214) (Chicago: Plenum).
3. Brown, R. (1977). Why are signed languages easier to learn than spoken languages? In W. C. Stokoe (ed.), Proceedings of the National Symposium on Sign Language Research and Teaching (pp. 9-24) (Silver Spring, MD: National Association of the Deaf).