8Vygotsky,L.S. Child psychology, in R.W. Rieber (Ed.). The collected works of Vygotsky. New York: Plenum Press, 1998.
9Duncan, R. M. & Tarulli, D. Play as leading activity of the preschool period: Insights from Vygotsky, Leont' ev, and Bakhtin. Early Education & Development, 2003, ( 14 ) : 271-292.
10Mahn, H. Periods in child development: Vygotsky's perspective. In Kozulin, A., & Gindins, B., & Ageyev, V. S., & Miller, S. M (Ed.). Vygotsky educational theory in cultural context. New York:Cambridge University Press, 2003:119-137.
