P. M. Thabede, N. D. Shooto, T. Xaba, and E. B. Naidoo, “Sulfuric Activated Carbon of Black Cumin (Nigella sativa L.) Seeds for the Removal of Cadmium(II) and Methylene Blue Dye”, ajc, vol. 32, no. 6, pp. 1361–1369, May 2020.