books.google.fr - Rising densities of human settlements, migration and transport to reduce distances to market, and specialization and trade facilitated by fewer international divisions are central to economic development. The transformations along these three dimensions density, distance, and division are most noticeable...https://books.google.fr/books/about/World_Development_Report_2009.html?id=ZkDE5CxAqHcC&utm_source=gb-gplus-shareWorld Development Report 2009