1. http://www.earthobservations.org/docs/10-Year%20Implementation%20Plan.pdf
2. http://qa4eo.org/docs/QA4EO_Principles_v4.0.pdf
3. CEOS Working Group on Calibration and Validation—Land Product Validation Subgrouphttp://lpvs.gsfc.nasa.gov/
4. Land Change Science;Gutman,2004
5. Vision;Marr,1982