Li Ge,  Existence of Solution for Four-Point Boundary Value Problems of Second-Order Impulsive Differential Equations (II).   journal   = {International Journal of Mathematical and Computational Sciences}, [online]. World Academy of Science, Engineering and Technology.
    July 2010, vol. 43(7). 826 - 830
    [viewed 27 April 2024]. Available from: https://publications.waset.org/pdf/3205.