Tawfiq, Luma N. M., and Samaher M. Yassien. “Solution of High Order Ordinary Boundary Value Problems Using Semi-Analytic Technique”. Ibn AL-Haitham Journal For Pure and Applied Sciences, vol. 26, no. 1, Apr. 2017, https://jih.uobaghdad.edu.iq/index.php/j/article/view/535.