W. A. Hamd Alla and  E. M. Shalaby and  R. A. Dawood and  A. A. Zohry,  Effect of Cowpea (Vigna sinensis L.) with Maize (Zea mays L.) Intercropping on Yield and Its Components.   journal   = {International Journal of Agricultural and Biosystems Engineering}, [online]. World Academy of Science, Engineering and Technology.
    January 2014, vol. 95(11). 1258 - 1264
    [viewed 09 April 2020]. Available from: https://publications.waset.org/pdf/10000250.