1. Farming, fertilizers and the nitrate problem;Addiscott,1991
2. Soil Organic Matter and Its Role in Crop Production;Allison,1973
3. CAP Reform: Management of set-aside land: research progress, Arable area payments;Clarke,1992
4. Rapport d'activités de la période 1987–1988;Commission des sols de Wallonie,1988
5. Nutrition;Draycott,1993