1. Maddison, A. Historical Statistics for the World Economy: 1-2001 AD, (2009). Available from: http://www.ggdc.net/maddison/. (Accessed 23 March, 2014).
2. Steffen, W., Crutzen, P.J., McNeill, J.R. The Anthropocene: are humans now overwhelming the great forces of nature? Ambio. 36(8), 614-621, (2007).
3. McNeill, J.R. Something New Under the Sun: An Environmental History of the Twentieth Century. Norton, New York, (2000).
4. Getchell, M. Investigating the Barriers to the Adoption of Solar Water Heating in Oregon MPP Essay. Submitted to Oregon State University. In partial fulfilment of the requirements for the degree of Master of Public Policy, (2013).
5. Diffusion of renewable energy technologies - barriers and stakeholders’ perspectives’;Reddy;Renewable Energy,2004