An asymptotic study of a weakly nonlinear multifrequency oscillating system. Neliniini Kolyvannya, [S. l.], v. 13, n. 3, p. 314–327, 2010. Disponível em: https://nosc.imath.kiev.ua/index.php/nosc/article/view/567. Acesso em: 12 apr. 2026.