MEDINA, Rigoberto; PINTO, Manuel. Conditionally integrable perturbations of linear differential systems. CUBO, A Mathematical Journal, [S. l.], n. 7, p. 01–15, 1991. Disponível em: https://cubo.ufro.cl/index.php/cubo/article/view/1824. Acesso em: 12 oct. 2025.