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2. P.A. Burrough: Principles of GIS in Land Res. Assess. Oxford University Press, Oxford, 1986
3. N. Bartelme: GIS Technologic Springer Verlag, Heidelberg 1989
4. S. Aronoff: Geographic Information Systems: A Management Perspective WDL Publications 1989
5. D.J. Peuquet & D.F. Marble: Introductory Readings in GIS. Taylor & Francis, London 1990