LI, S.; SU, J. Existence of multiple solutions of a two-point boundary value problem at resonance. Topological Methods in Nonlinear Analysis, [S. l.], v. 10, n. 1, p. 123–135, 1997. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.1997.025. Acesso em: 22 jul. 2024.