Principles of geographic information systems ITC core module di 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