For citations:

Mukhamadiev E., Naimov A.N. On a priori estimate of periodic solutions of a system of nonlinear ordinary differential equations of the second order. Izvestiya Vysshikh Uchebnykh Zavedenii. Matematika. 2024;(8):45-54. (In Russ.) https://doi.org/10.26907/0021-3446-2024-8-45-54