BarannykT. A., BarannykA. F., and YurykI. I., “Exact solutions of the nonliear equation $u_{tt} = = a(t) uu_{xx} + b(t) u_x^2 + c(t) u $”, Ukr. Mat. Zhurn., vol. 69, no. 9, pp. 1180-1186, Sep. 2017.