Reza Ghiasvand, Ali, et al. “Synthesis of a New Hydroxytriazene Derivative and Its Application for Selective Extraction- Spectrophotometric Determination of Nickel(II)”. Asian Journal of Chemistry, vol. 18, no. 3, Mar. 2010, pp. 2185-93, https://asianpubs.org/index.php/ajchem/article/view/20973.