1. Newell, A. and Simon, H.A. (1972) Human Problem Solving. Prentice-Hall, Englewood Cliffs, NJ.
2. Simon, H.A. (1978) Information-processing theory of human problem solving, in Handbook of Learning and Cognitive Processes: Volume 5: Human information Processing (edited by W.K. Estes), Erlbaum, Hillsdale, NJ, pp. 271-95.