theory," Journal of Symbolic Logic, v. 10, pp. 109–124. Ulrich Kohlenbach, 2008, Applied proof theory, Springer. John Myhill, 1973, "Some properties of Intuitionistic Zermelo-Fraenkel set theory", in A. Mathias and H. Rogers, Cambridge Summer School in Mathematical Logic, Lectures Notes in Mathematics v. 337, pp. 206–231, Springer. Michael Rathjen, 2005, "The Disjunction and Related Properties for Constructive Zermelo-Fraenkel Set Theory", Journal of Symbolic Logic, v. 70 n. 4, pp. 1233–1254. Anne S. Troelstra, ed. (1973), Metamathematical investigation of intuitionistic arithmetic and analysis, Springer. External links Intuitionistic Logic by Joan Moschovakis, Stanford Encyclopedia of Philosophy Proof theory Constructivism (mathematics)