DINH, Nguyen Van. The Poincare method for a strongly nonlinear Duffing oscillator. <b>Vietnam Journal of Mechanics</b>, Hanoi, Vietnam, v. 25, n. 1, p. 19–25, 2003. DOI: 10.15625/0866-7136/25/1/6575. Disponível em: https://vjmech.vast.vn/vjmech/article/view/6575. Acesso em: 9 nov. 2025.