1. “New Views on Intellectual Development”, unpublished paper, 1964.
2. The Process of Education, Harvard University Press, Cambridge, Massachusetts, 1961.
3. “Recent Developments in the Experimental Analysis of Learning and Concept Formation”, in New Dimensions in Learning, A.S.C.D., Washington, D.C., 1962, pp. 46–65.
4. A Study of Developmental Changes in Conceptual and Perceptual Associative Clustering