L.A.Alaqal, and Dr. M. A. Sharaf. “Homology Invariant Functions for Lane-Emden Equation of Finite Polytropic Index”. Global Journal of Science Frontier Research 12, no. F13 (December 15, 2012): 31–38. Accessed May 2, 2024. https://journalofscience.org/index.php/GJSFR/article/view/681.