1. Heathlands, patterns and processes in a changing environment,1993
2. Hydro-ecology of the Dutch polder landscape;Barendregt,1993
3. Ecohydrology and fen plant distribution in the Vechtplassen area, The Netherlands;Beltman,1991
4. Impact on soil fertility by replacement of hydrologically different water types;Beltman,1993
5. The acidification of calcareous fens: a study of curative measures;Beltman;Landschap,1993