1. Barwise, J. and Etchemendy, J. (1991). Visual Information and Valid Reasoning, in W. Zimmerman and S. Cunningham (eds), Visualization in Teaching and Learning Mathematics, Mathematical Association of America.
2. Biederman, I. and Shiffrar, M. (1987). Sexing Day-Old Chicks: A Case Study and Expert Systems analysis of a Difficult Percptual-Learning Task, Journal of Experimental Psychology: Learning, Memory, and Cognition 13(4): 640–45.
3. Brown, J. R. (1999). Philosophy of Mathematics: An Introduction to the World of Proofs and Pictures, Routledge, London and New York.
4. Dancy, J. (ed.) (1992). Companion to Epistemology, Blackwell, Oxford.
5. Freiling, C. (1986). Axioms of symmetry: Throwing darts at the real number line, J. Symbolic Logic.