PerestyukN. A. 2003. “Conditions for the Existence of Nonoscillating Solutions of Nonlinear Differential Equations With Delay and Pulse Influence in a Banach Space”. Ukrains’kyi Matematychnyi Zhurnal 55 (6), 790-98. https://umj.imath.kiev.ua/index.php/umj/article/view/3953.