WASET
    Y. Long and  L. Liu and  K. V. Branin,  Mixed Integer Programing for Multi-Tier Rebate with Discontinuous Cost Function.   journal   = {International Journal of Industrial and Systems Engineering}, [online]. World Academy of Science, Engineering and Technology.
    June 2018, vol. 135(3). 329 - 336
    [viewed 16 April 2024]. Available from: https://publications.waset.org/pdf/10009207.