OMAROVA, B.; SARTABANOV, Z. On Multiperiodic Solutions of Perturbed Nonlinear Autonomous Systems with the Differentiation Operator on a Vector Field. Eurasian Mathematical Journal, [S. l.], v. 12, n. 1, p. 68–81, 2021. DOI: 10.32523/2077-9879-2021-12-1-68-81. Disponível em: https://emj.enu.kz/index.php/main/article/view/206. Acesso em: 30 sep. 2026.