VANNELLA, G. Some qualitative properties of the solutions of an elliptic equation via Morse theory. Topological Methods in Nonlinear Analysis, [S. l.], v. 9, n. 2, p. 297–312, 1997. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.1997.015. Acesso em: 25 apr. 2024.