1. G. Gentzen, ?Consistency of pure number theory,? in: The Mathematical Theory of Logical Deduction [in Russian], Nauka, Moscow (1967).
2. K. Gödel, ?An as yet unemployed extension of the finitary point of view,? in: The Mathematical Theory of Logical Deduction [in Russian], Nauka, Moscow (1967).
3. E. A. Derevyankina, ?Some questions on the completeness of arithmetic,? Sib. Mat. Zh.,15, No. 2, 299?317 (1974).
4. A. G. Dragalin, ?Computability of primitive recursive terms of finite type and primitive recursive realization,? in: Zap. Nauch. Semin. Leningr. Otd. Matem. Inst. Akad. Nauk SSSR,8, 32?45 (1968).
5. A. G. Dragalin, ?The use of classical calculi for determination of constructive truth,? Vestn. Mosk. Univ. Mat. Mekh., No. 2, 25?29 (1972).