Doan Van Dien, and Pei-Hwa HUANG. “TIME-FREQUENCY ANALYSE FOR INTER-AREA OSCILLATIONS OF LONGITUDINAL POWER SYSTEM”. UTEHY Journal of Applied Science and Technology, Vol. 28, Jan. 2021, pp. 84-90, http://tapchi.utehy.edu.vn/index.php/jst/article/view/414.