1. A language for the description of concepts. Unpublished dittoed paper, Systems Research Center, Case Institute of Technology, 1964.
2. Remembering, a study in experimental and social psychology. Cambridge: Cambridge University Press, 1932.
3. , & A study of thinking. New York: John Wiley, 1956.
4. Aspects of the theory of syntax. Cambridge: M.I.T. Press, 1965.