ZHAI, QING-ZHOU. “Spectrophotometric Determination of Trace Amount of Oxalic Acid Based on Zirconium(IV)-(DBM-Arsenazo)- Oxalic Acid System”. Asian Journal of Chemistry, vol. 19, no. 2, Mar. 2010, pp. 1148-52, https://asianpubs.org/index.php/ajchem/article/view/20202.