KOLOMIYETS, V. G.; SAMOILENKO, A. M.; SAMOILENKO, V. G. The Third Bogolyubov Readings. International Scientific Conference “Asymptotic and Qualitative Methods in the Theory of Nonlinear Oscillations”. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 50, n. 4, p. 599, 1998. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4931. Acesso em: 5 dec. 2025.