1. Ando, A., Fisher, F. M., and Simon, H. A. Essays on the Structure of Social Science Models (Cambridge, Massachusetts: MIT Press, 1963). (See also Chapter 4.2 in this volume.)
2. Ramsey, Diane M., ed., Molecular Coding Problems, (New York: New York Academy of Sciences, 1967) pp. 120–121.
3. Simon, H. A., The Sciences of the Artificial, (Cambridge, Mass.: MIT Press, 1969).