1. Kyoto Protocol to the United Nations Framework Convention on Climate Changehttp://unfccc.Int/resource/docs/convkp/kpeng.pdf
2. Institute for Energy Research. Renewable Energyhttp://instituteforenergyresearch.org/topics/encyclopedia/renewable-energy/
3. 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 2001/77/EC and 2003/30/EC;Off. J. Eur. Union,2009
4. 10 Years of Renevable Energy Progress. Report of Renewable Energy Policy Network for the 21st Century (REN21)http://www.ren21.net/portals/0/documents/activities/topical%20reports/Ren21_10yr.pdf