Ukom, A.N., P.C. Ojimelukwe, and D.A. Okpara. 2009. “Nutrient Composition of Selected Sweet Potato [Ipomea Batatas (L) Lam] Varieties As Influenced by Different Levels of Nitrogen Fertilizer Application”. Pakistan Journal of Nutrition 8 (11): 1791–1795. https://doi.org/10.3923/pjn.2009.1791.1795.