Turing, A.M., On Computable Numbers, with an Application to the Entscheidungsproblem, Proceedings of the London Mathematical Society, 2 42, 1936, 42: 230–651937, doi:10.1112/plms/s2-42.1.230
Turing, A.M., On Computable Numbers, with an Application to the Entscheidungsproblem: A correction, Proceedings of the London Mathematical Society, 2 43 (6), 1938, 43 (6): 544–61937, doi:10.1112/plms/s2-43.6.544