Fatemeh Dadkhah and  Hossein Ali Akbarpour,  Scheduling a Flexible Flow Shops Problem using DEA.   journal   = {International Journal of Mathematical and Computational Sciences}, [online]. World Academy of Science, Engineering and Technology.
    January 2012, vol. 61(1). 69 - 73
    [viewed 11 May 2021]. Available from: https://publications.waset.org/pdf/13334.