1. United States Census Bureau—International Databasehttp://www.census.gov/population/international/data/idb/region.php?N=%20Results%20&T=13&A=aggregate&RT=2&Y=2013&R=301&C=
2. United States Census Bureau—International Databasehttp://www.census.gov/population/international/data/idb/region.php?N=%20Results%20&T=13&A=aggregate&RT=2&Y=2050&R=301&C=
3. United States Census Bureau—International Databasehttp://www.census.gov/population/international/data/idb/region.php?N=%20Results%20&T=13&A=aggregate&RT=2&Y=2030&R=301&C=
4. Global Health Observatory (GHO)—Urban population growthhttp://www.who.int/gho/urban_health/situation_trends/urban_population_growth_text/en/