1. An Inconvenient Truth website (2007). Accessed at http://www.climatecrisis.net/takeaction/carboncalculator/# July 9,2007.
2. Fisk, Umbra (2003). Plane Text. Accessed at http://www.grist.org/advice/ask/2003/05/28/umbra-airplanes/ July 9, 2007.
3. Department of Energy (2000). Carbon Dioxide Emissions from the Generation of Electric Power in the United States. Accessed at http://www.eia.doe.gov/cneaf/electricity/page/co2_report/co2report.html July 9, 2007.
4. Energy Information Administration (2002). Updated State-level Greenhouse Gas Emission Coefficients for Electricity Generation. Accessed at http://tonto.eia.doe.gov/FTPROOT/environment/e-supdoc-u.pdf July9, 2007.
5. McAliney, Mike (1993). Arguments for Land Conservation: Documentation and Information Sources for Land Resources Protection. Trust for Public Land; Sacramento, CA. As sited by www.coloradotrees.org 2007.
6. USDA Forest Service Pamphlet #R1-92-100 (2007). As sited by www.coloradotrees.org