@MANUAL {AJEIGBE:2010f, title = {Improved cowpea-cereal cropping systems: cereal-double cowpea system for the northern Guinea Savanna zone}, author = {Ajeigbe, H. and Singh, B. B. and Musa, A. and Adeosun, J. O. * and Adamu, R. S. * and Chikoye, D. }, year = {2010}, note = {Cropping Systems; Learning Material; ISBN: 978-978-49796-3-4; 17p.}, }