shoga, mehdi, hoseinzadeh lotfi, farhad, غلام ابری, امیر, Rashidi Komijan, Alireza (2020). Efficiency of 4 stage supply chain in presence of non discretionary , undesirable and negative factors Using SBM model in DEA. *Economic Modeling*, 14(51), 73-98. 10.30495/eco.2020.1899015.2357