Омарова , Б.Ж. “MULTIPERIODIC SOLUTIONS OF SECOND-ORDER SYSTEMS WITH DIFFERENTIATION OPERATOR ON THE LYAPUNOV’S VECTOR FIELD”. Bulletin of Abai KazNPU. Series of Physical and mathematical sciences 69, no. 1 (June 3, 2021): 155–163. Accessed November 28, 2024. https://bulletin-phmath.kaznpu.kz/index.php/ped/article/view/235.