1. Recommendations for a system to monitor critical indicators in areas prone to desertification;Berry,1977
2. CORINE—Soil Erosion Risk and Important Land Resources in the Southern Regions of the European Community;CEC,1992
3. Desertification of Arid Lands;Dregne,1983
4. Metodologı́a Provisional Para la Evaluación y la Representación Cartográfica de la Desertización;FAO/UNEP,1984
5. World Map of Desertification;FAO/UNEP/UNESCO/WMO,1977