HU, Zhigang; LIU, Wenbin. Solvability of a Coupled System of Fractional Differential Equations with Periodic Boundary Conditions at Resonance. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 65, n. 11, p. 1463–1475, 2013. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2526. Acesso em: 5 dec. 2025.