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2. Barnes , N. 2007 Home is where the airport is Business Week http://www.businessweek.com/print/magazine/content/07_34/b4047434.htm?chan=gl
3. World-city network: a new metageography?;Beaverstock;Annals of the Association of American Geographers,2000
4. Berg , E.N. 1985 UPS wings way into next-day letter service The Courier-Journal