Hu, J., Yamada, K., Sakanushi, T., Nakui, Y. and Atsuta, Y. 2012. 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, 1 (Jul. 2012), 37–46. DOI:https://doi.org/10.37936/ecti-eec.2013111.170607.