WASET
    K.-H. Yang,  Supplier Selection by Bi-Objectives Mixed Integer Program Approach.   journal   = {International Journal of Industrial and Manufacturing Engineering}, [online]. World Academy of Science, Engineering and Technology.
    April 2017, vol. 125(5). 611 - 615
    [viewed 27 April 2024]. Available from: https://publications.waset.org/pdf/10007276.