ZHANG, L.; TIAN, H. New fixed point theorems for sum operators in set $P_{h,e}$ and their applications to nonlinear fractional differential problems. Topological Methods in Nonlinear Analysis, [S. l.], v. 59, n. 2B, p. 719–735, 2022. DOI: 10.12775/TMNA.2021.008. Disponível em: https://apcz.umk.pl/TMNA/article/view/37958. Acesso em: 19 apr. 2024.