1. Beklemishev L.D. Parameter Free Induction and Provably Total Computable Functions // Theor. Computer Sci. 1999. V. 224(1Ts2). P. 13Ts33.
2. Beklemishev L.D. Proof-theoretic Analysis by Iterated Reflection // Arch. Math. Logic. 2003. V. 42. P. 515Ts552. DOI: 10.1007/ s00153-002-0158-7.
3. Beklemishev L.D. Provability Algebras and Proof theoretic Ordinals, I // Ann. Pure and Appl. Logic. 2004. V. 128. P. 103Ts123.
4. Beklemishev L.D. Reflection Principles and Provability Algebras in Formal Arithmetic // Rus. Math. Surv. 2005.V. 60(2). P. 197Ts268 (Ѕeklemishev. Ћ.ƒ. // ”ћЌ. 2005. “. 60. No 2. —. 3Ts72).
5. Beklemishev L.D., Visser A. On the Limit Existence Principles in Elementary Arithmetic and 0 ?n -Consequences of Theories // Ann. Pure Appl. Logic. 2005. V. 136. No 1/2. P. 56Ts74.
6. Cai. M. Higher Unprovability. 2015.
7. Feferman S. Transfinite Recursive Progressions of Axiomatic Theories // J. Symbolic Logic. 1962. V. 27. P. 259Ts316.
8. Ignatiev K.N. On Strong Provability Predicates and the Associated Modal Logics // J. of Symbolic Logic. 1993. V. 58. P. 249Ts290.
9. Japaridze G.K. The Modal Logical Means of Investigation of Provability. Thesis in Philosophy. Moscow, 1986.
10. Kreisel G., Levy A.  ? Reflection Principles and Their Use for Establishing the Complexity of Axiomatic Systems // Ztschr. math. Logik und Grundlagen. Math. 1968. V. 14. P. 7Ts142.
11. Smoryn ?ski C. Self-Reference and Modal Logic. Springer-Verlag, B.: 1985.
12. Turing A.M. System of Logics Based on Ordinals // Proc. London Math. Soc. Ser. 2. 1939. V. 45. P. 161Ts228.