T. Daood, Luma, Hanan H. Ahmed, and Khalida M. Omar. “Spectrophotometric Determination of Yttrium With Pyrocatechol Violet Reagent – Application to Water”. Rafidain Journal of Science 21, no. 6 (September 1, 2010): 18–30. Accessed December 3, 2025. https://earth.uomosul.edu.iq/index.php/rsci/article/view/47710.