GRIGORIEVA, S. V.; USHAKOV, V. N. Use finite family of multivalued maps for constructing stable absorption operator. Topological Methods in Nonlinear Analysis, [S. l.], v. 15, n. 1, p. 75–89, 2000. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.2000.006. Acesso em: 29 mar. 2024.