1. Investigations in the local qualitative theory of differential equations at the chair of differential equations of Petersburg University;A. F. Andreev,1999
2. Yu. N. Bibikov and V. A. Pliss, “The existence of invariant tori in the neighborhood of the zero solution of a system of ordinary differential equations,” Differ. Uravn. 3 (11), 1864–1881 (1967).
3. Yu. N. Bibikov, Local Theory of Nonlinear Analytic Ordinary Differential Equations (Springer-Verlag, New York, 1979), in Ser.: Lecture Notes in Mathematics, Vol. 702.
4. Yu. N. Bibikov, Multi-Frequency Nonlinear Oscillations and Their Bifurcations (Leningr. Gos. Univ., Leningrad, 1991) [in Russian].
5. Yu. N. Bibikov, V. R. Bukaty, and N. V. Trushina, “On the stability of the equilibrium under periodic perturbations of an oscillator with a power-law restoring force with a rational exponent,” J. Appl. Math. Mech. 80, 443–448 (2016).