1. United Nations Environmental Programme, Global Environment Outlook – 6 Regional Reports, http://www.unep.org/geo/news/geo-6-regional-reports-launched. [accessed September 01, 2017].
2. United Nations. World Population Prospects: The 2010 Revision: Highlights and Advance Tables, UN Department of Economic and Social Affairs: Population Division, New York; 2011.
3. International Energy Agency. World Energy Outlook 2010, OECD/IEA, Paris, France; 2010.
4. Forecasting of the Consumption of Metals up to 2050;Halada;Materials Transactions,2008
5. T.Gardner-Outlaw, R. Engleman. Sustaining Water, Easing Scarcity: A Second Update, Population Action International (PAI), Washington DC;1997.