LU, S.; XUE, R. Periodic solutions for a singular Liénard equation with indefinite weight. Topological Methods in Nonlinear Analysis, [S. l.], v. 54, n. 1, p. 203–218, 2019. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.2019.037. Acesso em: 20 apr. 2024.