MAWHIN, J. Resonance and nonlinearity: A survey. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 59, n. 2, p. 190–205, 2007. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3303. Acesso em: 6 dec. 2025.