1. ArcWorld;Environmental Systems Research Institute (ESRI),1992
2. Digital chart of the world;Environmental Systems Research Institute (ESRI),1993
3. Shuttle Radar Topography Mission produces a wealth of data;Farr;Eos Trans. AGU,2000
4. New land surface digital elevation model covers the Earth;Gesch;Eos Trans. AGU,1999
5. International Centre for Tropical Agriculture (CIAT), , , ( 2004, ), Void-filled seamless SRTM data, , Cali, Colombia., (Available at http://srtm.csi.cgiar.org)