Anh, Vu Quoc, and Nghiem Manh Hien. “Geometric Nonlinear Vibration Analysis of Steel Frames With Semi-Rigid Connections and Rigid-Zones”. Vietnam Journal of Mechanics 25, no. 2 (June 30, 2003): 122–128. Accessed October 8, 2024. https://vjs.ac.vn/index.php/vjmech/article/view/6584.