On Periodic Solutions for Implicit Problem with Nonlinear Fractional Differential Equation Involving the Riesz-Caputo Fractional Derivative. Letters in Nonlinear Analysis and its Applications, [S. l.], v. 4, n. 1, p. 44–59, 2026. Disponível em: https://lettersinnonlinearanalysis.com/index.php/lnaa/article/view/74. Acesso em: 14 may. 2026.