Pelyukh, G. P., & Samoilenko, A. 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.
https://umj.imath.kiev.ua/index.php/umj/article/view/5604