Rethinking natural resource degradation in Sub-Saharan Africa :
Rethinking natural resource degradation in Sub-Saharan Africa : policies to support sustainable soil fertility management, soil and water conservation among resource-poor farmers in semi-arid areas / edited by Tom Slaymaker ; Roger Blench - Tamale: Cyber Systems, 2002. - 2 volumes : ill. (some color) ; 25 cm