1. J. Barwise and J. Etchemendy. Heterogeneous logic. In J. Glasgow, N.H. Narayan, and B. Chandrasekaran, editorsDiagrammatic Reasoning: Cognitive and Computational Perspectivespages 211–234. MIT Press, Cambridge, 1995.
2. D.G. Bobrow. Dimensions of representation. In D.G. Bobrow and A. Collins, editorsLanguage
Thought and Culture: Advances in the Study of Cognitionpages 1–34. Academic Press, New York, 1975.
3. N. Goodman. Languages of Art. Hackett, Indianapolis, second edition, 1984.
4. P.J. Hayes. Some problems and non-problems in representation theory. In R.J. Brachman and H.J. Levesque, editorsReadings in Knowledge Representation.Morgan Kaufmann, Los Altos, 1985.
5. S.M. Kosslyn. Image and Mind, chapter 2. Harvard University Press, Cambridge, 1980.