Dinh, Nguyen Van. “On a Variant of the Asymptotic Procedure (for Weakly Nonlinear Autonomous Systems)”. <i>Vietnam Journal of Mechanics</i> 25, no. 2 (June 30, 2003): 77–84. Accessed November 8, 2025. https://vjmech.vast.vn/vjmech/article/view/6580.