Zheng, H., Fan, W., Xie, W., Ji, F., Tan, M. and Yang, C. (2013) “Catalytic Spectrophotometric Determination of Ultra Trace-level Copper(II) with Indigo Carmine”, Asian Journal of Chemistry, 25(17), pp. 9547-9550. Available at: https://asianpubs.org/index.php/ajchem/article/view/8547 (Accessed: 3July2022).