1. Argus, 2011. Asphalt Report. November 11, 2011.
2. ASTM International, 2008. Standard Practice for Roads and Parking Lots Pavement Condition Index Surveys, Designation: D 6433-07, January 2008.
3. 2.6: Limiting climate change to 450ppm CO2 equivalent in the 21st century;Calvin;Energy Economics,2009
4. Colorado Department of Transportation, 2010. 2010 Cost Data Construction, July 27, 2010.
5. Congressional Budget Office, 2007. Trends in Public Spending on Transportation and Water Infrastructure, 1956–2004 August.