ABDELJABBAR GHANMI. Existence of Positive Solutions for a Coupled System of Nonlinear Fractional Di erential Equations. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 71, n. 1, p. 37–46, 2023. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/6008. Acesso em: 5 dec. 2025.