Echioda, S., A. O. Ogunieye, S. Salisu, A. A. Abdulrasheed, I. Y. Chindo, and A. M. Kolo. “UV-Vis Spectrophotometric Determination of Selected Heavy Metals (Pb, Cr, Cd and As) in Environmental, Water and Biological Samples With Synthesized Glutaraldehyde Phenyl Hydrazone As the Chromogenic Reagent”. European Journal of Advanced Chemistry Research, vol. 2, no. 3, July 2021, pp. 1-5, doi:10.24018/ejchem.2021.2.3.59.