Vlasenko, L. A., and A. M. Samoilenko. “Optimal Control With Impulsive Component for Systems Described by Implicit Parabolic Operator Differential Equations”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 61, no. 8, Aug. 2009, pp. 1053-65, https://umj.imath.kiev.ua/index.php/umj/article/view/3080.