1) US Environmental Protection Agency, Cap and Trade: Basic Information, http://www.epa.gov/captrade/basic-info.html

2) Greenpeace, Quickfacts – Key climate and energy issues for the US and Canada, http://www.greenpeace.org/canada/en/recent/greenpeace-welcomes-president-obama/quickfacts/

3) Hansen, J., Mki. Sato, P. Kharecha, D. Beerling, R. Berner, V. Masson-Delmotte, M. Pagani, M. Raymo, D.L. Royer, and J.C. Zachos, 2008: Target atmospheric CO2: Where should humanity aim? Open Atmos. Sci. J., 2, 217-231, doi:10.2174/1874282300802010217. http://www.giss.nasa.gov/research/briefs/hansen_13/

4) Environment Canada, Turning the Corner: Regulatory Framework for Industrial Greenhouse Gas Emissions, http://www.ec.gc.ca/doc/virage-corner/2008-03/541_eng.htm#target