"Technology". Carbon Recycling International. 2011. Archived from the original on 17 June 2013. Retrieved 2012-07-11.
doi.org
Demirbas, A. . (2009). "Political, economic and environmental impacts of biofuels: A review". Applied Energy. 86: S108–S117. doi:10.1016/j.apenergy.2009.04.036.
iea.org
"Publications"(PDF). www.iea.org. Archived from the original(PDF) on 18 March 2009. Retrieved 2016-01-07.