BarannykT. A.; BarannykA. F.; YurykI. I. Exact solutions of the nonliear equation $u_{tt} = = a(t) uu_{xx} + b(t) u_x^2 + c(t) u $. Ukrains’kyi Matematychnyi Zhurnal, v. 69, n. 9, p. 1180-1186, 25 Sep. 2017.