NIZHNIK, L. P.; SAMOILENKO, A. M. Differential Equations with Bistable Nonlinearity. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 67, n. 4, p. 517–554, 2015. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2001. Acesso em: 5 dec. 2025.