1. Energy – Consumption “Consumption by fuel, 1965–2008” (XLS), Statistical Review of World Energy 2009, BP. July 31, 2006 (accessed 24.10.09).
2. Global Energy Review; 2009. Enerdata Publication.
3. Global warming, http://en.wikipedia.org/wiki/Global_warming; 2011 (accessed 02.11.11).
4. “Renewables in global energy supply: an IEA facts sheet”, IEA/OECD; 2007.
5. Solar heating and cooling for a sustainable energy future in Europe (Revised), European solar thermal technology platform (ESTTP), http://www.estif.org/fileadmin/estif/content/projects/downloads/ESTTP_SRA_RevisedVersion.pdf; 2009.