Gh. Afshar, Z., and H. Parham. “Determination of Trace Amounts of Benzalkonium Chloride by Liquid-Liquid Extraction-Spectrophotometry Method”. Asian Journal of Chemistry, vol. 23, no. 10, Aug. 2011, pp. 4464-6, https://asianpubs.org/index.php/ajchem/article/view/10880.