On formally undecidable propositions of the Principia Mathematica and related systems ; On undecidable propositions of formal mathematical systems ; On intuitionistic arithmetic and number theory ; On the length of proofs ; Remarks before the Princeton Bicentennial Conference on Problems in Mathematics / Kurt Gödel
An unsolvable problem of elementary number theory ; A note on the entscheidungsproblem / Alonzo Church
On computable numbers, with an application to the entscheidungsproblem ; Systems of logic based on ordinals / Alan M. Turing
An informal exposition of proofs of Gödel's theorem and Church's theorem ; Extensions of some theorems of Gödel and Church / J.B. Rosser
General recursive functions of natural number ; Recursive predicates and quantifiers / Stephen C. Kleene
Finite combinatory processes: formulation I ; Recursive unsolvability of a problem of Thue ; Recursively enumerable sets of positive integers and their decision problems ; Absolutely unsolvable problems and relatively undecidable propositions: account of an application / Emil Post.