Festus K. Akinnifesi, Gudeta Sileshi, Steven Franzel, Oluyede C. Ajayi, Rebbie Harawa, Wilkson Makumba, Sesbastian Chakeredza, Simon Mngomba, Judith J. de Wolf and Jonas N. Chianu
Agricultural Journal 4 ( 6 ): 260 - 271 , 2009