Bel’skiiD. V., and PelyukhG. P. “Asymptotic Estimates for the Solutions of a Differential-functional equation With Linear Delay”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 71, no. 1, Jan. 2019, pp. 129-38, http://umj.imath.kiev.ua/index.php/umj/article/view/1424.