S. Elabbas, L. Mandi, F. Berrekhis, M. N. Pons, J. P. Leclerc, N. Ouazzani. 2016. Removal of Cr (III) from chrome tanning wastewater by adsorption using two natural carbonaceous materials: Eggshell and powdered marble. Journal of Environmental Management, 166, 589-595, 2016