Barannyk, T. A., A. F. Barannyk, and I. I. Yuryk. 2017. “Exact Solutions of the Nonliear Equation $u_{tt} = = a(t) uu_{xx} + b(t) u_x^2 + c(t) U $”.
Ukrains’kyi Matematychnyi Zhurnal 69 (9): 1180-86.
https://umj.imath.kiev.ua/index.php/umj/article/view/1768.