Omarova, Bibigul, and Zhaishylyk Sartabanov. “On Multiperiodic Solutions of Perturbed Nonlinear Autonomous Systems With the Differentiation Operator on a Vector Field”. Eurasian Mathematical Journal 12, no. 1 (March 30, 2021). Accessed November 21, 2025. https://emj.enu.kz/index.php/main/article/view/206.