World City Networks andHierarchies,1977-1997:Empirical Analysis of Global Air TravelLinks .2 Smith,D.A,Timberlake,M. American Behavioral Scientist . 2001
World City Networks andHierarchies,1977-1997:Empirical Analysis of Global Air TravelLinks .2 Smith,D.A,Timberlake,M. American Behavioral Scientist . 2001