1. U.S. Energy Information Administration Oil: Crude and Petroleum Products, Refinery Rankings. [Accessed 20 January 2018]. https://www.eia.gov/energyexplained/index.cfm?page=oil_refining#tab4.
2. Warrick, J. “Utilities Wage Campaign Against Rooftop Solar” The Washington Post, 7 March 2015. [Accessed 15 January 2018]. https://www.washingtonpost.com/national/health-science/utilities-sensing-threat-put-squeeze-on-booming-solar-roof-industry/2015/03/07/2d916f88-c1c9-11e4-ad5c-3b8ce89f1b89_story.html?utm_term=.f25ee0aba123.
3. Prosperity in the age of decline;Beaulieu,2014
4. The new rules of green marketing: strategies, tools, and inspirations for sustainable branding;Ottman,2011
5. Ecovadis Mission Statement. http://www.ecovadis.com/about-us/. [Accessed 5 January 2018].