Asiegbu, J. E., and J. O. Uzo. “Yield and Yield Component Responses of Vegetable Crops to Farmyard Manure Rates in the Presence of Inorganic Fertili”. The Journal of Agriculture of the University of Puerto Rico 68, no. 3 (July 1, 1984): 243–252. Accessed August 17, 2022. https://revistas.upr.edu/index.php/jaupr/article/view/7283.