1. European Commission (EC). Directive 2009/28/EC of the European Parliament and of the Council of 23 April 2009 on the Promotion of the Use of Energy from Renewable Sources and Amending and Subsequently Repealing Directives 2001/77EC and 2003/30/EC, 2009/28/EC,Official Journal of the European Union, 2009.
2. International Energy Agency (IEA)Renewable Energy Medium-Term Market Report 2014;International Energy Agency (IEA):Paris, France, 2014; p255;http://www.iea.org/publications/freepublications/publication/medium-term-renewable-energy-market-report-2014.html.
3. Zah, R., Böni, H., Gauch, M., Hischier, R., Lehmann, M., and Wäger, P.Ökobilanz von Energieprodukten: Ökologische Bewertung von Biotreibstoffen;Swiss Federal Office of Energy (SFOE):Bern, Switzerland, 2007; p161;http://www.news.admin.ch/NSBSubscriber/message/attachments/8514.pdf.
4. Consequential life cycle assessment of biogas, biofuel and biomass energy options within an arable crop rotation