K. C., R. and Alam M., S. 2004. Effect of higher approximation of Krylov-Bogoliubov-Mitropolskii’s solution and matched asymptotic solution of a differential system with slowly varying coefficients and damping near to a turning point. Vietnam Journal of Mechanics. 26, 3 (Oct. 2004), 182–192. DOI:https://doi.org/10.15625/0866-7136/26/3/5702.