@ARTICLE {GUTIERREZ:1997,
title = {Quantitative assessment of traditional cropping systems in the Sudan savanna of northern Nigeria: I. Rapid survey of prevalent cropping systems},
author = {Henriet, J and van Ek, G. A. and Blade, S. and Singh, B. },
journal = {Samaru Journal of Agricultural Research},
year = {1997},
volume = {14},
pages = {37--45},
}