Sani, H. A.; Tsafe, A.; Bagudo, B.; Itodo, A. Toxic Metals Uptake by Spinach (Spinacea Oleracea) and Lettuce (Lactuca Sativa) Cultivated in Sokoto: A Comparative Study. Pak. J. Nutr. 2011, 10 (6), 572–576. https://doi.org/10.3923/pjn.2011.572.576.