Fedorchuk, V. M. “Symmetry Reduction and Some Exact Solutions of a Nonlinear Five-Dimensional Wave Equation”. Ukrains’kyi Matematychnyi Zhurnal 48, no. 4 (April 25, 1996): 573–576. Accessed December 5, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/5324.