1. U.S. Energy Information Administration (EIA), Monthly Energy Review, U.S. Department of Energy, Washington, D.C., 2014
2. W. V.
Houten
, Department of Defense Energy Policy, United States Department of Defense, 2009
3. U.S. Energy Information Administration (EIA), Most States have Renewable Portfolio Standards - Today in Energy, http://www.eia.gov/todayinenergy/detail.cfm?id=4850
4. United States Environmental Protection Agency, Renewable Fuel Standard (RFS), 2011, http://www.epa.gov/otaq/fuels/renewablefuels/index.htm
5. U.S. Energy Information Administration (EIA), Annual Energy Outlook 2014, 2014