Li, J.Y. (2011) Based on the Development of the Industry Association of China’s Express Delivery Industry Research. Shanghai Normal University, Shanghai.
 Peng, L.C. (2011) Analysis of the Advantages and Disadvantages of China’s Express Industry Development. Market Modernization, 656, 40-41.
 Wang, L.H. (2012) Based on GM(1,1) Model to Forecast China’s Revenue from Express Service. Logistics Technology, 31, 84-86.
 Cao, M.X. (2007) Research on Grey Incidence Analysis Model and Its Application. Nanjing University of Aeronautics and Astronautics, Nanjing.
 Wang, W.T. and Huang, B.Z. (2011) An Empirical Study of Influencing Factors in the Express Industry Development. China Logistics & Purchasing, 13, 74-75.
 Deng, J.L. (1990) The Grey System Theory Tutorial. Huazhong University of Science and Technology Press Co., Ltd., Wuhan.
 (2014) China Statistical Yearbook. National Bureau of Statistics of China, Beijing.
 Xu, G.X. (2008) Statistical Forecasting and Decision-Making. 3rd Edition, Shanghai University of Finance & Economics Press Co., Ltd., Shanghai.
 Wu, H.R. (1990) Applied Grey Model to Forecast Business Volume of Postal and Postal and Telecommunication Services. Journal of Nanjing Institute of Posts and Telecommunications, 10, 91-94.
 Ji, T. (2012) Analysis of Influencing Factors on Express Industry. Nanjing University of Posts and Telecommunications, Nanjing.