1. EIA 2006 U.S. Energy Information Administration
2. Watkins K 2006 Human Development Report
3. Jacobson M Z and Delucchi M A 2011 Energy Policy 391154
4. Jacobson M Z, Delucchi M A, Bazouin G, Bauer Z A F, Heavey C C, Fisher E et al 2015 Energy Environ. Sci. 8 2093
5. http://www.nrel.gov/gis/solar.html