Bahaa, G. M., and M. M. Tharwat. “Time-Optimal Control of Infinite Variables Parabolic Systems With Time Lags Given in Integral Form”. Advances in Systems Science and Applications, vol. 11, no. 1-2, Mar. 2011, pp. 1-26, https://ijassa.ipu.ru/index.php/ijassa/article/view/288.