1. Bialosz S., 1997, Soil mapping, Land degradation, Proc. FAO/ESA in cooperation with BASA Workshop for Decision-Makers on Remote Sensing/GIS Applications to Agricultural and Environmental Management, St. Kyrick-Assenovgrad, Bulgaria.
2. Bondev A., 1991, Rastitelnosta na Bulgaria (Vegetation of Bulgaria), map 1:600000, Sofia.
3. Committee of Geology, Republic of Bulgaria, 1989, Geological Map of Bulgaria 1: 500 000.
4. Dallemand J.F., Lichtenegger J., 1994, Use of ERS-1 SAR data for Agricultural and Environmental Applications in Central-Eastern Europe, Proc. ESA/ESRIN, Workshop, November 1993, Frascati.
5. Di Gregorio A., Jansen L., 2000, Land Cover Classification System (LCCS): Classification Concepts and User manual for software version 1.0, Food and Agriculture Organisation of the United Nations, Rome.
6. European Soil Bureau, 1998, Geo-referenced Soil Database for Europe, Manual of Procedures, version 1.0.
7. FAO, 1997, Revised Legend of the Soil Map of the World.
8. FAO, 1999, Strengthening Capacity in Agricultural Development through Remote Sensing and GIS, Project Document TCP/BUL/8922.
9. FAO, 1999, Provincial Landcover Atlas of Islamic State of Afghanistan, FAO/UNDP Project AFG/90/02.
10. Le Bas, Jamagne M., 1996, Soil database to support sustainable development, JRC Ispra, Orleans.
11. Milenova L., Nedkov R., Pironkova Z., Vassilev V., Milenov P., Radkov R., 9-10 Nov 2000, Land Cover Mapping using satellite images and GIS technologies, International symposium on “Application of Geodetic and Information technologies in the physical planning of the territories”, Sofia.
12. Ministry of Environment, Republic of Bulgaria, 1997, Pilot Environmental Management Plan for an Outlying Area of Sofia, Final Report.
