Neuman W L.Social Research Methods:Qualitative andQuantitative Approaches,5th Edition.Boston:Allyn&Ba-com,2003.
[2]
Masser I.Government and Geographic Information.Lon-don:Taylor&Francis,1998.
[3]
Kong Y,Lin H.China's national geographic informationstrategy:lessons learnt from first generation initiators.InXu G,Chen Y(eds.),Toward Digital Earth:Proceedings ofthe International Symposium on Digital Earth.Beijing,1999,167~176.