1. The geography of the United states in the year 2000;Berry,1975
2. Estimates of world GDP, one million B.C.—present;De Long,1998
3. The origins of political order: From prehuman times to the French revolution;Fukuyama,2011
4. Triumph of the city;Glaeser,2011
5. Autonomous taxis could greatly reduce greenhouse-gas emissions of US light-duty vehicles;Greenblatt;Nature Climate Change,2015