1. Brouwers, J.H.A.M., 1993. Rural People's Response to Soil Fertility Decline: The Adja Case (Benin). PhD thesis, Wageningen Agricultural University, Wageningen, The Netherlands.
2. Spatial variability in soil fertility management and crop response in Mutoko communal area, Zimbabwe;Carter;Ambio,1995
3. Rural Appraisal: Rapid, Relaxed and Participatory. IDS discussion paper No. 331;Chambers,1992
4. Defoer, T. (2000) Moving Methodologies: Learning about Integrated Soil Fertility Management in Sub-Saharan Africa. Forthcoming PhD thesis, Wageningen Agricultrual University, Wageningen, The Netherlands.
5. Managing Soil Fertility in the Tropics: A Resource Guide for Participatory Learning and Action Research,2000