Ali Taher, Mohammad. 2010. “Derivative Spectrophotometric Determination of Trace Manganese After Separation and Preconcentration With the Ion Pair of 2-(5-Bromo-2-Pyridylazo)-5-Diethylaminophenol and Ammonium Tetraphenylborate ”. Asian Journal of Chemistry 14 (1):107-16. https://asianpubs.org/index.php/ajchem/article/view/21959.