Approximate controllability of fractional semilinear control system of order $\alpha\in (1,2]$ in Hilbert spaces. Nonlinear Studies, [S. l.], v. 22, n. 1, 2015. Disponível em: https://www.nonlinearstudies.com/index.php/nonlinear/article/view/1026. Acesso em: 17 sep. 2025.