Li Xiguang, Positive Solutions for Boundary Value Problems of Fourth-Order Nonlinear Singular Differential Equations in Banach Space. journal = {International Journal of Mathematical and Computational Sciences}, [online]. World Academy of Science, Engineering and Technology. September 2013, vol. 76(4). 762 - 766 [viewed 23 September 2024]. Available from: https://publications.waset.org/pdf/17068.