Jena, D., and M. Vijay. “A Comparison of PI Tuning by Direct Search and Genetic Algorithm for Optimal Control of AGC in Continuous-Discrete Mode”. Power Research - A Journal of CPRI, Sept. 2012, pp. 113–122, https://node6473.myfcloud.com/~geosocin/CPRI/index.php/pr/article/view/374.