‘Tracer Studies and groundwater Recharge Assessment in the Eastern Fringe of the Botswana Kalahari: The LetlhakengBotlhapatlou Area’, ‘Recharge of Phreatic Aquifers in (Semi-) Arid Areas’, ‘Grondwater in Nederland’
2 januari 1998 Michael van der Valk Editie 1998 - 2
