PelyukhG. P., & SamoilenkoA. M. (1994). Solutions of systems of nonlinear difference-differential equations of neutral type asymptotically bounded in the entire axis. Ukrains’kyi Matematychnyi Zhurnal, 46(11), 1597-1601. Retrieved from https://umj.imath.kiev.ua/index.php/umj/article/view/5604