1. Abu Sin , M. E. H. R. J. Davies The Future of Sudan's Capital Region: A Study in Development and Change Khartoum Univ. Press Khartoum, Sudan 1991
2. Alhassan , W. S. The potential of sorghum straw as a livestock feed in Nigeria Symposium on the Current Status and Potential of Industrial Uses of Sorghum in Nigeria, 4-6 December 1989, Kano, Nigeria Int. Crops Res. Inst. for the Semi-Arid Trop. (ICRISAT) Zaria, Nigeria 1990
3. Emission of trace gases and aerosols from biomass burning;Andreae;Global Biogeochem. Cycles,2001
4. Areola , O. Ecology of Natural Resources in Nigeria Gower Brookfield, Vt. 1991