1. Chemical Analysis of Ecological Materials;Allen,1974
2. The Inland Waters of Tropical Africa;Beadle,1981
3. Determination of Sulphur in Soils and Plant Material;Beaton,1968
4. Sulphates in African waters;Beauchamp;Nature,1953
5. Nutrient cycling in a Carex lacustris wetland;Bernard;Can. J. Bot.,1976