Pelyukh, G. P., and A. M. Samoilenko. “Solutions of Systems of Nonlinear Difference-Differential Equations of Neutral Type Asymptotically Bounded in the Entire Axis”. Ukrains’kyi Matematychnyi Zhurnal 46, no. 11 (November 25, 1994): 1597-1601. Accessed June 2, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/5604.