Islam, M. Z., Alam, M. S., & Hossain, M. B. (2008). A unified Krylov-Bogoliubov-Mitropolskii method for solving hyperbolic-type nonlinear partial differential systems. Vietnam Journal of Mechanics, 30(1), 11–19. https://doi.org/10.15625/0866-7136/30/1/5607