Omarova, B. and Sartabanov, Z. 2021. On Multiperiodic Solutions of Perturbed Nonlinear Autonomous Systems with the Differentiation Operator on a Vector Field. Eurasian Mathematical Journal. 12, 1 (Mar. 2021), 68–81. DOI:https://doi.org/10.32523/2077-9879-2021-12-1-68-81.