Friedberg, R. (1958). A Learning Machine, Part I IBM Journal of Research and Development 2, No. 1.
McCarthy, John (1956). The Inversion of Functions Defined by Turing Machines, in Automata Studies, Annals of Mathematical Study No. 34, Princeton, pp. 177-181.
Minsky, M.L. (1956). Heuristic Aspects of the Artificial Intellegence Problem. Lincoln Laboratory Report,pp.34-55.
Newell, A., Shaw, J. C. and Simon, H.A.(1957). Empirical Explorations of the Logic Theory Machine. A case Study in Heuristic. Proceedings of the Western Joint Computer Conference, published by the Institute of Radio Engineers, New York, 1957, pp. 218-230.