1. Baroody, A. J., & Ginsburg, H. P. (1982). Preschoolers’ informal mathematical skills. American Journal of Diseases of Children, 136, 195–197.
2. Baroody, A. J., & Price, J. (1983). The development of the number-word sequence in the counting of three-year-olds. Journal for Research in Mathematics Education, 14, 361–368.
3. Braine, M. D. S., & Rumain, B. (1983). Logical reasoning. In J. H. Flavell, & E. M. Markman (Eds.), Handbook of child psychology: Vol. 3. Cognitive development (pp. 263–340). New York: Wiley.
4. Carpenter, T. P., & Moser, J. M. (1982). The development of addition and subtraction problem-solving skills. In T. P. Carpenter, J. M. Moser, & T. A. Romberg (Eds.), Addition and subtraction: A cognitive perspective (pp. 9–24). Hillsdale, NJ: Erlbaum.
5. Ferrara, R. A. (1987). Learning mathematics in the zone of proximal development: The importance of flexible use of knowledge. Doctoral dissertation, University of Illinois at Urbana-Champaign.