1. Association of American Railroads, 2007. National Rail Freight Infrastructure Capacity and Investment Study (September).
2. American Association of State Highway and Transportation Officials, 2003. Freight–Rail Bottom Line Report. (retrieved 03.01.11).
3. Direct and indirect water withdrawals for US industrial sectors;Blackhurst;Environmental Science & Technology,2009
4. Development and applications of GREET 2.7 – The Transportation Vehicle-Cycle Model;Burnham,2006
5. Congressional Budgetary Office, 2007. Trends in Public Spending in Transportation and Water Infrastructure, 1956 to 2004. Congress of the United States, Congressional Budge Office.