CLAPP, M.; SZULKIN, A. Solutions to indefinite weakly coupled cooperative elliptic systems. Topological Methods in Nonlinear Analysis, [S. l.], v. 59, n. 2A, p. 553–568, 2021. DOI: 10.12775/TMNA.2020.052. Disponível em: https://apcz.umk.pl/TMNA/article/view/35206. Acesso em: 22 jul. 2024.