Koval’chukT. V., KravetsV. I., Mohyl’ovaV. V., and StanzhitskiiA. N. 2018. “Application of the method of Averaging to the Problems of Optimal Control over Functional-Differential Equations”. Ukrains’kyi Matematychnyi Zhurnal 70 (2), 206-15. http://umj.imath.kiev.ua/index.php/umj/article/view/1551.