Ukiwe, L. N., J.I, A., A.E, E., C.I.C, A. and S.I, I. (2008) “Chemical and Biological Leaching Methods to Remove Heavy Metals from Sewage Sludge: A Review”, JOURNAL OF ADVANCES IN CHEMISTRY, 4(3), pp. 509–517. doi: 10.24297/jac.v4i3.948.