Njiti, M. M., Usman, Y., & Ngala, A. L. (2018). Water Use Efficiency of Selected Cowpea Cultivars (Vigna unguiculata (L.) Walp) Grown on Residual Soil Moisture in Northeast Nigeria. International Journal of Environment, Agriculture and Biotechnology, 3(4), 1473–1485. https://doi.org/10.22161/ijeab/3.4.45