@article{
  author = {Vatani, Sepideh},
  title = {Evaluation of efficiency using the product method in two-stage systems with undesirable outputs},
  journal = {International Journal of Data Envelopment Analysis},
  year = {2021},
  volume = {9},
  issue = {2},
  pages = {55-64},
  doi = {10.30495/ijdea.2022.68507.1169},
  url = {https://sanad.iau.ir/fa/Article/826329}
}