Existence and Uniqueness of Positive Solutions for a System of Multi-Order Fractional Differential Equations. Communications in Mathematical Research, [S. l.], v. 32, n. 3, p. 249–258, 2021. DOI: 10.13447/j.1674-5647.2016.03.07. Disponível em: https://global-sci.com/index.php/cmr/article/view/8895. Acesso em: 27 feb. 2026.