1. Ballou RH 1999Business Logistics Management4th edn, (Prentice Hall)
2. DeJong KA 1975 An analysis of the behavior of a class of genetic adaptive system Doctoral dissertation, University of Michigan
3. Saaty TL 1980The Analytic Hierarchy Process(New York: McGraw-Hill)
4. Saaty TL 1994Fundamentals of Decision Making and Priority Theory with the Analytic Hierarchy Process(The Analytic Hierarchy Process Series, 6)
5. UPS Logistics Group 2001 United Parcel Service of America, Inc http://www.upslogistics.com