LI, Z.; SHEN, Y.; ZHANG, Y. An application of nonsmooth critical point theory. Topological Methods in Nonlinear Analysis, [S. l.], v. 35, n. 2, p. 203–219, 2010. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.2010.012. Acesso em: 25 apr. 2024.