1. BP Statistical Review of World Energy, 〈bp.com/statisticalreview〉; June 2013 [accessed on 13/8/2013].
2. 〈http://www.treia.org〉 [accessed on 6/6/2013].
3. Renewable energy: markets and prospects by technology;Brown;Int Energy Agency Inf Paper,2011
4. Renewable energy today and tomorrow;Bull;Proc IEEE,2001
5. RE-thinking 2050, 〈www.erec.org〉 [accessed on 02/9/2013].