7Hwang, C. L. , K. Yoon. Multiple Attribute Decision Making Methods and Applications :A State-of-the-art Survey [M]. Berlin : Springer-Verlag, 1981 : 35- 78.
8TriantaphyIlou, E. Multi-criteria Decision Making Methods : A Comparative Study[M]. Dordrecht: Kluwer Academic Publishers, 2000 : 44- 59.