Chinyere Nwankpa, A. “Determination of Food Crops Contamination in Osun State, Nigeria Due to Radium-226, Thorium-232 and Potassium-40 Concentrations in the Environment”. European Journal of Sustainable Development, vol. 6, no. 4, Oct. 2017, p. 169, doi:10.14207/ejsd.2017.v6n4p169.