Gödel was one of four authors who had personally read and approved the translations of his works. This approval process was laborious. Gödel introduced changes to his text of 1931, and negotiations between the men were "protracted": "Privately van Heijenoort declared that Gödel was the most doggedly fastidious individual he had ever known." Between them they "exchanged a total of seventy letters and met twice in Gödel's office in order to resolve questions concerning subtleties in the meanings and usage of German and English words." (Dawson 1997:216-217). Although not a translation of the original paper, a very useful 4th version exists that "cover[s] ground quite similar to that covered by Godel's original 1931 paper on undecidability" (Davis 1952:39), as well as Gödel's own extensions of and commentary on the topic. This appears as On Undecidable Propositions of Formal Mathematical Systems (Davis 1965:39ff) and represents the lectures as transcribed by Stephen Kleene and J. Barkley Rosser while Gödel delivered them at the Institute for Advanced Study in Princeton, New Jersey in 1934. Two pages of errata and additional corrections by Gödel were added by Davis to this version. This version is also notable because in it Gödel first describes the Herbrand suggestion that gave rise to the (general, i.e. Herbrand-Gödel) form of recursion. References Stefan Bauer-Mengelberg (1966). Review of The Undecidable: Basic Papers on Undecidable Propositions, Unsolvable problems and Computable Functions. The Journal of Symbolic Logic, Vol. 31, No. 3. (September 1966), pp. 484–494. Alonzo Church (1972). Review of A Source Book in Mathematical Logic 1879–1931. The Journal of Symbolic Logic, Vol. 37, No. 2. (June 1972), p. 405. Martin Davis, ed. (1965). The Undecidable: Basic Papers on Undecidable Propositions, Unsolvable Problems and Computable Functions, Raven, New York. Reprint, Dover, 2004. . Martin Davis, (2000). Engines of Logic: Mathematics and the Origin of the Computer, W. W. Norton & Company, New York. pbk. Kurt Gödel (1931), "Über formal unentscheidbare Sätze der Principia Mathematica und verwandter Systeme I". Monatshefte für Mathematik und Physik 38: 173–198. . Available online via SpringerLink. Kurt Gödel (1958). "Über eine bisher noch nicht benüzte Erweiterung des finiten Standpunktes". Dialectica v. 12, pp. 280–287. Reprinted in English translation in Gödel's Collected Works, vol II, Soloman Feferman et al., eds. Oxford University Press, 1990. Jean van Heijenoort, ed. (1967). From Frege to Gödel: A Source Book on Mathematical Logic 1879–1931. Harvard University Press. Bernard Meltzer (1962). On Formally Undecidable