On computable numbers, with an application to the Entscheidungsproblem
Alan Mathison Turing
Journal of Mathematics, pp. 345-363
Rounding-off errors in matrix processes
Alan Mathison Turing
The Quarterly Journal of Mechanics and Applied Mathematics, vol. 1(1), 1948, pp. 287-308
Computability and lambda-definability (1937)
Alan Mathison Turing
Journal of Mathematics, vol. 2(4), 1937 Dec, pp. 153-163