Principles of geographic information systems ITC core module حسب By, Rolf A., Sc, M.C. Ellis B., Kainz, D.W, Knippers, R.A, Kraak, M.J, Krol, B.G.C.M, Radwan, M.M, Sides, E.J, Sun, Y., Weir, M.J.C, Van Westen, C.J