1. The classification of soils as used by French pedologists in tropical or arid areas;AUBERT;Afr. Soils,1964
2. The determination of organic carbon in soil using a probe colorimeter;BAKER;Lab. Practice,1976
3. BLOKHUIS , W. A. OCHTMAN , L. H. J. PETERS , K. H. 1964 Vertisols in the Gezira and the Khashm el Girba clay plains, Sudan Trans. 8th Int. Congr. Soil Sci. Bucharest
4. D'HOORE , J. L. 1964 Soil map of Africa 1: 5,000,000 explanatory monograph, Commission for Technical Co-operation in Africa. Lagos