Spectrophotometric determination of zinc in pharmaceutical samples using di-2-pyridyl ketone salicyloylhydrazone - Gaubeur, Ivanise; Areias, Madalena Carneiro da Cunha; Terra, Lúcia Helena Silveira Ávila; Suárez-Iha, Maria Encarnación Vazquez (Spectroscopy Letters, 2002)