1. World energy outlook 2009;IEA,2009
2. Biofuels – at what cost? Government support for ethanol and biodiesel in the European Union;GSI (The Global Subsidies Initiative),2007
3. World energy outlook 2006;IEA,2006
4. World ethanol markets, the outlook to 2015;Lichts,2006
5. Directive for the promotion of renewables;CEC,2008