Controllability and qualitative property results for Ambartsumian equation via chi- Hilfer generalized proportional fractional derivative on time scales. Nonlinear Studies, [S. l.], v. 29, n. 4, 2022. Disponível em: https://nonlinearstudies.com/index.php/nonlinear/article/view/3084. Acesso em: 31 dec. 2025.