1. A. G. Dragalin, Mathematical Intuitionism. Introduction to Proof Theory (Nauka, Moscow, 1979) [in Russian].
2. S. C. Kleene and R. E. Vesley, The Foundations of Intuitionistic Mathematics, Especially, in Relation to Recursive Functions (North-Holland, Amsterdam, 1965; Nauka, Moscow, 1978).
3. S. C. Kleene, An Introduction to Metamathematics (Van Nostrand, New York, 1952; Inostrannaya Literatura, Moscow, 1957).
4. T. Jech, Set Theory (Springer, Berlin, 2003).
5. H. Friedman, “The consistency of classical set theory relative to a set theory with intuitionistic logic,” J. Symbolic Logic 38, 315–319 (1973).