1. Dispatchability Versus Sustainability Loughborough;Gammon,2010
2. International data base estimates updated. December 2009;U.S. Census Bureau,2009
3. 2008 World population data sheet;Haub,2008
4. 2007 World population data sheet, 2006 estimate;Haub,2007
5. 2006 World population data sheet, 2005 estimate;Haub,2006