1. Badger, Emily. 2013. “The Most Important Population Statistic That Hardly Ever Gets Talked About.” City Lab (formerly The Atlantic Cities), May 30.
2. Population Distribution During the Day
3. Biggs, John. 2013. “A Tiny Computer Attracts a Million Tinkerers.” The New York Times, January 30, B8
4. Models of core/periphery structures
5. Bureau of Transportation Statistics. 2017. “Load Factor – Passenger-Miles as a Proportion of Available Seat-Miles in Percent.” US Department of Transportation. https://www.transtats.bts.gov/Data_Elements.aspx?Data=5