Frege and Gödel : two fundamental texts in mathematical logic - Gödel, Kurt (Kurt Friedrich), 1906-1978; Van Heijenoort, Jean (Jean Louis Maxime), 1912-1986; Frege, Gottlob (Friedrich Ludwig Gottlob), 1848-1925 (Cambridge (Mass.) : Harvard university press, 1970)
Begriffsschrift, a formula language, modeled upon that of arithmetic, for pure thought (1879), by G. Frege.--Some metamathematical results on completeness and consistency; On formally undecidable propositions of Principia mathematica and related systems I; and On completeness and consistency (1930b, 1931, and 1931a), by K. Gödel.--Bibliography (p. [111]-116)
"These texts, in English translation, originally appeared in From Frege to Gödel: a source book in mathematical logic, 1879-1931."
Keywords: Logic, Symbolic and mathematical; Mathematics -- Philosophy