VitrychenkoI. E. “On Oscillation of Solutions of a Nonautonomous Quasilinear Second-Order Equation”. Ukrains’kyi Matematychnyi Zhurnal 46, no. 4 (April 25, 1994): 347–356. Accessed November 24, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/5731.