6Spekman R E, Hill R. Strategy for effective procurement in the 1980s [J]. International Journal of Purchasing and Materials Management, 1980, 16(4): 2-7.
7Berger P D, Gerstenfeld A, Zeng A A. How many suppliers are best? A decision-analysis approach [J]. Omega, 2004, 32(1): 9-15.
8Ruiz-Torres A J, Mahmoodi F. The optimal number of suppliers considering the costs of individual suppliers failures [J]. Omega, 2007, 35(1): 104-115.
9Goh M, Lim J Y S, Meng F W. A stochastic model for risk management in global supply chain networks [J]. European Journal of Operational Research, 2007, 182(1): 164-173.
10Crosier R B. Multivariate generalizations of cumulative sum quality-control schemes rics, 1988, 30: 291-303.
