TUDUNWADA, I. Y.; ESSIET, E. U.; MOHAMMED, S. G. THE EFFECTS OF TANNERY SLUDGE ON HEAVY METALS CONCENTRATION IN CEREALS ON SMALL-HOLDER FARMS IN KANO, NIGERIA. Notulae Botanicae Horti Agrobotanici Cluj-Napoca, v. 35, n. 2, p. 55-60, 5 Aug. 2007.