@INPROCEEDINGS {PLEYSIER:1987a, title = {Extraction of cations from some kaolinitic soils of the tropics}, author = {Pleysier, J. L. and Janssens, J. and Cremers, A. }, editor = {Pleijsier, L. K. }, booktitle = {Proceedings of an International Workshop on the Laboratory Methods and Data Exchange Programme}, year = {1987}, pages = {51--66}, publisher = {International Soil Reference and Information Centre}, address = {Wageningen}, }