Safira, A. K., A. Sa’adah, R. Sulvianuri, and Y. Agnesia. “Analysis of Nonlinear Oscillation Models With External Forcing Using the Multiple Scales Method”. Rangkiang Mathematics Journal, vol. 5, no. 1, Apr. 2026, pp. 79-90, doi:10.24036/rmj.v5i1.138.