ysics Reports, Volume 424, Issues 4-5, February 2006, Pages 175-308 12 A larger hunger: Brandon Fuller and Paul Romer “Urbanization as Opportunity,” Marron Institute Working Paper No. 1, 2014 13 These expanding, ever-thicker webs: See Castells, Manuel. Communication Power. Oxford, UK: Oxford University Press, 2009; and Castells,