Arora, H.C., and R.C. Sexena. “Solvent Extraction and Determination of Yttrium in Geological Samples by Atomic Absorption Spectrophotometry ”. Asian Journal of Chemistry, vol. 1, no. 1, Mar. 2010, pp. 75-78, https://asianpubs.org/index.php/ajchem/article/view/25372.