ROMANENKO, O. Yu.; SHARKOVSKY, O. M. Dynamics of solutions of the simplest nonlinear boundary-value problems. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 51, n. 6, p. 810–826, 1999. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4668. Acesso em: 27 apr. 2025.