1. Allison JR (1992) The economics of using legumes in cropping systems. In Mulongoy KM Gueye M and Spencer DSC (eds) Biological Nitrogen Fixation and Sustainability of Tropical Agriculture, pp 323–333. John wiley, Chichester
2. Anderson LS and Sinclair FL (1993) Ecological interactions in agroforestry systems. Agrofor Abstr 6: 57–91
3. Anon (1990) Recently completed co-ordinated research programme. Soils Newsletter Joint FAO-IAEA Division, Vienna 13: 6–8
4. Armitage FB (1985) Irrigated Forestry in Arid and Semi-arid Lands: a Synthesis. International Development Research Centre, Ottawa
5. Audru J, Labonne M, Guérin H and Bilha A (1993) Acacia nilotica. Son intérêt fourrager et son exploitation chez leséleveurs Afars de la vallée du Madgoul à Djibouti. Bois For Trop 235: 59–70