CORVELLEC, Jean-Noël. On the second deformation lemma. Topological Methods in Nonlinear Analysis, [S. l.], v. 17, n. 1, p. 55–66, 2001. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.2001.004. Acesso em: 4 feb. 2026.