GeoENV I : geostatistics for environmental applications : proceedings of the Geostatistics for environmental applications workshop, Lisbon, Portugal, 18-19 November 1996 / ed. by Amílcar Soares, Jaime Gómez-Hernandez and Roland FroidevauxGeoENV II : Geostatistics for Environmental Applications : proceedings of the second European Conference on Geostatics for Environmental Applications held in Valencia, Spain, November 18-20, 1998 / ed. by Jaime Gómez-Hernández, Amílcar Soares and Roland Froidevaux