van Duivenbooden, N and Pala, M and Studer, C and Bielders, C L, eds. (1999) Efficient soil water use: the key to sustainable crop production in the dry areas of West Asia, and North and Sub-Shararan Africa: proceedings of the Workshop, Niamey, Niger, 26-30 April 1998 and proceedings of the Workhop, Amman, Jordon, 9-13 May 1999. International Center for Agricultural Research in the Dry Areas, Aleppo, Syria. ISBN 9290664003