Benshi Zhu,  Positive Solutions for a Class of Semipositone Discrete Boundary Value Problems with Two Parameters.   journal   = {International Journal of Mathematical and Computational Sciences}, [online]. World Academy of Science, Engineering and Technology.
    October 2010, vol. 46(10). 1370 - 1376
    [viewed 21 January 2020]. Available from: https://publications.waset.org/pdf/16003.