4UNITED NATIONS, Department of Economic and Social Affairs, Population Division. 2012. World Urbanization Prospects: The 2011 Revision[ R/CD]. CD-ROM Edition.
5UNITED NATIONS, Department of Economic and Social Affairs, Population Division. 2013. World Population Prospects: The 2012 Revision[ R/OL]. http://esa.un.org/wpp/unpp/panel_ indicators.htm.