Hu, Jie, Kou Yamada, Tatsuya Sakanushi, Yuki Nakui, and Yusuke Atsuta. “A Design Method for Control System to Attenuate Periodic Input Disturbances Using Disturbance Observers for Time-Delay Plants”. ECTI Transactions on Electrical Engineering, Electronics, and Communications 11, no. 1 (July 12, 2012): 37–46. accessed September 18, 2026. https://ph02.tci-thaijo.org/index.php/ECTI-EEC/article/view/170607.