Yuekun Chen and  Yousef Sardahi and  Salam Hajjar and  Christopher Greer,  Multi-Objective Optimal Design of a Cascade Control System for a Class of Underactuated Mechanical Systems.   journal   = {International Journal of Mechanical and Mechatronics Engineering}, [online]. World Academy of Science, Engineering and Technology.
    April 2020, vol. 161(5). 196 - 202
    [viewed 13 August 2020]. Available from: https://publications.waset.org/pdf/10011222.