1. Alazard D, Ndoye I and Dreyfus B 1988 Sesbania rostrata and other stem nodulated legumes. In Nitrogen Fixation: A Hundred Years. Eds. H Bothe, F J de Bruijn and W E Newton. pp 765?769. Gustav Fischer, Stuttgart, Germany.
2. Allen O N and Allan E K 1981 The Leguminosae: A Source Book of Characteristics, Uses and Nodulation. University of Wisconsin Press, Madison. 812p.
3. Anonymous 1975 Root activity patterns of some tree crops: Results of a Five-Year Coordinated Research Programme of the Joint FAO/IAEA Division of Atomic Energy in Food and Agriculture. STI/DOC/10/170, IAEA, Vienna. Austria.
4. Baker D D, Wheeler R A, and Fried M 1990 Estimation of biological dinitrogen fixation by 15N-dilution in tree plantations. I. Sampling strategies and first harvest results for three legume species. Paper presented at fourth African Association for Biological Nitrogen Fixation. International Institute of Tropical Agriculture, Ibadan, Nigeria, 24?28 September 1990.
5. Barnet Y M, Catt P C and Hearne D H 1985 Biological nitrogen fixation and root-nodule bacteria (Rhizobium sp. and Bradyrhizobium sp.) in two rehabilitating sand dune areas planted with Acacia spp. Aust. J. Bot. 33, 595?610.