Aliyu, H. “Studies on Cu (II) and Ni (II) Sulphate Chelates of Benzyl, Salicylic and Acetyl Salicylo-Hydrazones: Synthesis of Cu (II) and Ni (II) Sulphate Complexes”. Biological Sciences - PJSIR, vol. 52, no. 6, Dec. 2009, pp. 312-5, https://v2.pjsir.org/index.php/biological-sciences/article/view/574.