Usman, M., M.G. Nangere, and S. D. Audu. 2018. “Advantages of Intercropping Cowpea With Maize Crop Under Different Tillage Methods and Inorganic Fertilizer Rates”. International Journal For Research In Agricultural And Food Science 4 (1):18-33. https://gnpublication.org/index.php/afs/article/view/330.