Cook WD, M Kress and LM Sheiford (1996). “Data Envelopment Analysis in the Presence of Both Quantitative and Qualitative Factors.” JORS 47(7): 945-953.
Cook WD, M Kress and LM Sheiford (1996). “Data Envelopment Analysis in the Presence of Both Quantitative and Qualitative Factors.” JORS 47(7): 945-953.