N. Popovich and  P. Yan,  Determination of Q and R Matrices for Optimal Pitch Aircraft Control.   journal   = {International Journal of Aerospace and Mechanical Engineering}, [online]. World Academy of Science, Engineering and Technology.
    February 2011, vol. 50(2). 445 - 451
    [viewed 01 April 2020]. Available from: https://publications.waset.org/pdf/9945.