KOVAL’CHUK, T. V.; KRAVETS, V. I.; MOHYL’OVA, V. V.; STANZHITSKII, A. N. Application of the method of averaging to the problems of optimal control over functional-differential equations. Ukrains’kyi Matematychnyi Zhurnal, v. 70, n. 2, p. 206-215, 25 Feb. 2018.