Zhu, Hui, Jing Niu, Ruimin Zhang, and Yingzhen Lin. “A New Approach for Solving Nonlinear Singular Boundary Value Problems”. Mathematical Modelling and Analysis 23, no. 1 (February 20, 2018): 33–43. Accessed January 8, 2026. https://journals.vilniustech.lt/index.php/MMA/article/view/225.