AIZICOVICI, S.; PAPAGEORGIOU, N. S.; STAICU, V. Existence and multiplicity of solutions for resonant nonlinear Neumann problems. Topological Methods in Nonlinear Analysis, [S. l.], v. 35, n. 2, p. 235–252, 2010. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.2010.014. Acesso em: 25 jan. 2022.