A. Monzeli, B. Daneshian, G. Tohidi, M. Sanei, and S. Razavyan, “Evaluating the Efficiency of Hospital Emergencies during COVID-19 Pandemic Crisis in the Presence of Undesirable Inputs in DEA”, Fuzzy Optim. Model. J., vol. 2, no. 3, pp. 47–55, Nov. 2021, doi: 10.30495/fomj.2021.1943126.1040.