6Chames A, Cooper W W, Rhodes H. Measuring the Effi- ciency of Decision Making Units [ J]. European Journal of Op- erational Research, 1978 (2) :429 - 444.
7Fare R, Grosskopf S, Norris M, Zhang Z. Productivity Growth, Technical Progress and Efficiency Change in Industri- alized Countries [ J ]. American Economic Review, 1994,84 : 66 -83.