3Charnes Abraham, William Wager Coop- er, Susan X Li. Using data envelopment anal- ysis to evaluate efficiency in the economic performance of Chinese cities [J]. Socio-E- conomic Planning Sciences, 1989(23).
4Charnes A, Cooper W W, Rhodes E. Measuring the efficiency of decision making units [J]. European Journal of Operational Research, 1978,2(6).