MAWHIN, J.; ZANOLIN, F. A continuation approach to fourth order superlinear periodic boundary value problems. Topological Methods in Nonlinear Analysis, [S. l.], v. 2, n. 1, p. 55–74, 1993. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.1993.030. Acesso em: 26 apr. 2024.