@inbook{NBERc7978,
 Crossref = "NBERglae08-1",
 title = "Estimating Agglomeration Economies with History, Geology, and Worker Effects",
 author = "Pierre-Philippe Combes and Gilles Duranton and Laurent Gobillon and Sébastien Roux",
 year = "2007",
 month = "December",
 URL = "http://www.nber.org/chapters/c7978",
}