1. Alckmin, G., Goldemberg, J., 2004. Assessment of Greenhouse Gas Emissions in the Production and Use of Fuel Ethanol in Brazil. URL: 〈http://www.unica.com.br/〉 (Acc. 2006-03-31)
2. Competing technologies, increasing returns and lock-in by historical events;Arthur,1989
3. Biofuels Research Advisory Council (BIOFRAC), 2006. Biofuels in the European Union: A Vision for 2030 and Beyond. URL: 〈http://europa.eu.int/comm/research/energy/〉 (Acc. 2006-03-31)
4. Techniques of validation in qualitative research: a critical commentary;Bloor,1997
5. Our Energy Future: Creating a Low Carbon Economy,2003