1. Arts , G.H.P. 1990 Deterioration of Atlantic Softwater Systems and Their Flora. A historical account Thesis University of Nijmegen 197
2. Bakker , J.P. 1989 Nature Management by Grazing and Cutting. On the ecological significance of grazing and cutting regimes applied to restore former species-rich plant communities in the Netherlands Thesis University of Groningen Kluwer 400
3. The Association Concept in the Braun-Blanquet School of Phytocoenology;Barkman;Biologisch Station Wijster, meded,1988a
4. Fidelity and character-species, a critical evaluation;Barkman;Vegetatio,1989a