1. BP, 2008. Statistical Review of Energy Resources. June.
2. Natural gas: the revolution is coming;Economides;JPT (May),2001
3. Herbst, M., 2007. Ethanol: too much hype—and corn. Business Week (1 February). http://www.businessweek.com/debateroom/archives/2007/02/ethanol_too_muc.html.
4. International Energy Agency, 2007a. World Energy Outlook.