共 3 条
[1]
Historical Perspectives on U.S.Economic Geography. Sukkoo Kim,Robert A.Margo. NBER Working Paper No. 9594 . 2003
[2]
Texas Transportation Institute. mobility.tamu.edu . 2005
[3]
Bus Systems for Future: Achieving Sustainable Transport Worldwide. L .Fulton,L. Schipper. . 2002