1. Use of Vertisols for rainfed sorghum in the Central Clay Plain in Sudan;Babiker,1989
2. Tillage Trials in Vertisols in the South Kordofan Region of Sudan;Berry,1982
3. QEN Water. Soil and Forestry — Assessments of the Problems and Programmes for Action;Dickinson,1983
4. Yield Response to Water;FAO,1979