Nkwopara, U. N., and H. Hu. “Sorption of Lead on Variable Charged Soils as Affected by Temperature and Time in Three Provinces of China.” International Journal of Environment, Agriculture and Biotechnology, vol. 3, no. 4, 2018, pp. 1486–92. Crossref, https://doi.org/10.22161/ijeab/3.4.46.