Hoang Trung Hien, Chuong Thiet Tu and Nguyen Hoai Son (2013) “Modal analysis for three dimensional frame structures element using FEM”, Journal of Technical Education Science, 8(1), pp. 65–72. Available at: https://www.jte.edu.vn/index.php/jte/article/view/683 (Accessed: 23 May 2026).