RAFFOUL, Youssef N. Boundedness and stability in nonlinear systems of differential equations using a modified variation of parameters formula. CUBO, A Mathematical Journal, [S. l.], p. 37–55, 2023. DOI: 10.56754/0719-0646.2501.037. Disponível em: https://cubo.ufro.cl/index.php/cubo/article/view/3329. Acesso em: 7 dec. 2025.