1. Arlin, P. (1974). Problem finding: The relation between cognitive process variables and problem finding performance. Unpublished doctoral dissertation, University of Chicago, Chicago.
2. Basseches, M. (1984). Dialectical thinking and adult development.Norwood, NJ: Ablex.
3. Bringuier, J. (1980).Conversations with Jean Piaget. Chicago: University of Chicago Press.
4. Chapman, M. (1988). Constructive evolution.New York: Cambridge University Press.