Groundwater vulnerability assessment and mapping : selected papers from the Groundwater Vulnerability Assessment and Mapping International Conference, Ustron, Poland, 2004 - Witkowski, Andrzej J.; Witkowski, Andrzej J.; Kowalczyk, Andrzej; Kowalczyk, Andrzej; Vrba, Jaroslav; Vrba, Jaroslav (Taylor & Francis, 2007)