Kanase, D.G., et al. “Synthesis, Spectral and XRD Studies on Isomeric Chelates of Strontium(II) and Barium(II) With Phthiocol and Plumbagin”. Asian Journal of Chemistry, vol. 16, no. 3, June 2016, pp. 1630-6, https://asianpubs.org/index.php/ajchem/article/view/14469.