Midodashvili, B., and S. Kharibegashvili. “On the Existence, Uniqueness, and Nonexistence of Solutions of One Boundary-Value Problem for a Semilinear Hyperbolic Equation”. Ukrains’kyi Matematychnyi Zhurnal 71, no. 8 (August 25, 2019): 1123–1132. Accessed December 6, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/1503.