Najafi, M., M. Moghimi, and H. Massah. “Analytical Treatment for Nonlinear Oscillation Equations and Vibratory System of Waves”. Tamkang Journal of Mathematics 40, no. 1 (March 31, 2009): 77–94. Accessed November 21, 2024. https://journals.math.tku.edu.tw/index.php/TKJM/article/view/38.