CORVELLEC, Jean-Noël; DEGIOVANNI, Marco; MARZOCCHI, Marco. Deformation properties for continuous functionals and critical point theory. Topological Methods in Nonlinear Analysis, [S. l.], v. 1, n. 1, p. 151–171, 1993. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.1993.012. Acesso em: 8 jul. 2025.