Zernov, A. E. “On the Solution of a Singular Cauchy Problem for a First-Order Differential Equation Unsolved With Respect to the Derivative of an Unknown Function”. Ukrains’kyi Matematychnyi Zhurnal 53, no. 2 (February 25, 2001): 258–262. Accessed April 11, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/4243.