1. United Nations-Department of Economic and Social Affairs (2014) World Urbanization Prospects. https://www.un.org/en/development/desa/publications/2014-revision-world-urbanization-prospects.html
2. United States-Census Bureau (2017) Southern Cities Growing Quickly. https://www.census.gov/library/visualizations/2017/comm/cb17-81-cities-growing.html
3. United States Census Bureau 2010 Census Urban and Rural Classification and Urban Area Criteria (2010). https://www.census.gov/programs-surveys/geography/guidance/geo-areas/urban-rural/2010-urban-rural.html
4. U.S. Department of Transportation, “Smart City Challenge”. https://www.transportation.gov/smartcity
5. Guy Allee, Smart America, “Smart Cities USA”. http://smartamerica.org/teams/smart-cities-usa/