Tamatamah , R. A. “Phosphorus Sorption in Relation to Soil Grain Size and Geochemical Composition in the Simiyu and Kagera River Basins, Tanzania”. Tanzania Journal of Science, vol. 31, no. 2, Apr. 2021, pp. 33-39, https://tjs.udsm.ac.tz/index.php/tjs/article/view/385.