Zhang, Xue-Hong, and Wen-Bin Chen. “Tween-80 Medium-Spectrophotometric Determination of Trace Ge(IV) With 1-(4-Antipyrine)-3-(2,4,6-Tribromo phenyl)triazene As Colour Reagent”. Asian Journal of Chemistry, vol. 25, no. 17, Nov. 2013, pp. 9805-7, doi:10.14233/ajchem.2013.15391.