Turing, Alan Mathison (1937). "On Computable Numbers, with an Application to the Entscheidungsproblem". Proceedings of the London Mathematical Society. Series 2. 42 (1): 230–265. doi:10.1112/plms/s2-42.1.230. S2CID73712.
Turing, Alan Mathison (1937). "On Computable Numbers, with an Application to the Entscheidungsproblem". Proceedings of the London Mathematical Society. Series 2. 42 (1): 230–265. doi:10.1112/plms/s2-42.1.230. S2CID73712.