Li, K.N. (2002) On Logistics Cost and GNP. China Business and Market, No. 4, 11-13.
 China Statistical Yearbook and China Logistics Yearbook (Data Has Been Calculated and Rearranged).
 Logistics Costs and US Gross Domestic Product, Prepared for: Federal Highway Administration Department of Transportation, Prepared by: MacroSys Research and Technology, Washington DC, 25 August 2005.
 WDI Database from the World Bank.
 US Department of Commerce Bureau of Economic Analysis.