DINH, N. V. On a variant of the asymptotic procedure (weakly nonlinear systems in a special cases). Vietnam Journal of Mechanics, Hanoi, Vietnam, v. 26, n. 3, p. 139–147, 2004. DOI: 10.15625/0866-7136/26/3/5698. Disponível em: https://vjs.ac.vn/index.php/vjmech/article/view/5698. Acesso em: 7 dec. 2021.