KHATSKEVICH, V. L. Periodic solutions of monotone differential inclusions with fast and slow variables. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 45, n. 5, p. 694–703, 1993. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5856. Acesso em: 17 apr. 2025.