Sneha M. Dodiya, and Jagrut Gadit. “Comparison of Fractional Order Proportional Integral Controller (FO-PI) and Integer Order Proportional Integral Controller (IO-PI)”. International Journal of Advance Engineering and Research Development (IJAERD), vol. 2, no. 5, May 2015, pp. 556-65, https://ijaerd.org/index.php/IJAERD/article/view/939.