1. Vertisols in the seasonally dry central clay plain in the Sudan;Abdulla Mohamed,1989
2. Physical properties of Ethiopian Vertisols;Woldeab,1988
3. Animal draught farm implements;Awadwhal;World Animal Review,1991
4. Use of Vertisols for sorghum in the central clay plain of Sudan;Babiker,1989
5. Bulk density changes in a cracking clay soil;Berndt;Aust. J. Soil Res.,1976