1. A. F. Izmailov and A. A. Tret’yakov, Factor Analysis of Nonlinear Maps (Nauka, Moscow, 1994) [in Russian].
2. A. F. Izmailov and A. A. Tret’yakov, 2-Regular Solutions of Nonlinear Problems: Theory and Numerical Methods (Fizmatlit, Moscow, 1999) [in Russian].
3. A. Tret’yakov and J. E. Marsden, “Factor analysis of nonlinear mappings: p-regularity theory,” Commun. Pure Appl. Anal. 2 (4), 425–445 (2003).
4. B. Medak and A. A. Tret’yakov, “Existence of periodic solutions to nonlinear p-regular boundary value problem,” Boundary Value Probl. 2015, 91 (2015).
5. B. Medak and A. A. Tret’yakov, Theory of p-Regularity: Analysis and Applications (Fizmatlit, Moscow, 2017) [in Russian].