1. United Nations. Sustainable development goals 2016. http://www.un.org/sustainabledevelopment/energy/ (accessed April 21, 2016).
2. United Nations - Department of Economic and Social Affairs Population Division. Population 2015. http://www.un.org/en/development/desa/population/ (accessed April 25, 2016).
3. Independent Statistics & Analysis - U.S. Energy Information Administration. Forecasts 2014. https://www.eia.gov/forecasts/ (accessed April 25, 2016).
4. Independent Statistics & Analysis - U.S. Energy Information Administration. International energy outlook 2016 - DOE/EIA-0484. 2016.
5. Climate change 2014: synthesis report;RK,2014