1. American Energy Information Administration EIA available at http://www.eia.gov/
2. 2012 The outlook for energy: a view to 2040, ExxonMobil's long-term view of the world's energy future 2012
3. World Energy Industry overview http://www.mbendi.com/indy/ener/p0005.htm
4. Renewables 2010 Global Status Report http://www.ren21.net/REN21Activities/Publications/GlobalStatusReport/GSR2010/tabid/5824/Default.aspx