@article{RO_2017__51_4_875_0,
     author = {Eydi, Alireza and Bakhtiari, Mahnaz},
     title = {A multi-product model for evaluating and selecting two layers of suppliers considering environmental factors},
     journal = {RAIRO - Operations Research - Recherche Op\'erationnelle},
     pages = {875--902},
     publisher = {EDP-Sciences},
     volume = {51},
     number = {4},
     year = {2017},
     doi = {10.1051/ro/2016070},
     mrnumber = {3783925},
     zbl = {1400.90003},
     language = {en},
     url = {http://archive.numdam.org/articles/10.1051/ro/2016070/}
}