Frederiksen, Peter. “Carl Christiansson: Soil Erosion and Sedimentation in Semi-Arid Tanzania: Studies of Environmental Change and Ecological Imbalance. (University of Stockholm. Department of Physical Geography. Meddelande. A Nr. 119)”. Geografisk Tidsskrift - Danish Journal of Geography, vol. 84, Jan. 1984, https://tidsskrift.dk/geografisktidsskrift/article/view/43999.