Edward Glaeser (2011). “Triumph of the City: How Our Greatest Invention Makes Us Richer, Smarter, Greener, Healthier and Happier”, p.136, Pan Macmillan
Grace Lee Boggs, Scott Kurashige, Danny Glover (2012). “The Next American Revolution: Sustainable Activism for the Twenty-First Century”, p.47, Univ of California Press