1. Psychological;Hull,1920
2. , and , A Study of Thinking, New York: Wiley, 1956.
3. Structure and Direction in Thinking, New York: Wiley, 1956.
4. “The concept of concept,” in Categories of Human Learning, (Ed.), New York: Academic, 1964.
5. and (Eds.), Piaget and His School: A Reader in Developmental Psychology, New York: Springer-Verlag, 1976.