DINH, N. V. On a variant of the asymptotic procedure (for weakly nonlinear autonomous systems). Vietnam Journal of Mechanics, Hanoi, Vietnam, v. 25, n. 2, p. 77–84, 2003. DOI: 10.15625/0866-7136/25/2/6580. Disponível em: https://vjs.ac.vn/index.php/vjmech/article/view/6580. Acesso em: 27 nov. 2021.