Abbasi. , K., M.Y. Khuhawar, and M.I. Bhanger. 2010. “Ethyl Chloroformate As Derivatizing Reagent for Gas Chromatographic Determination of Norephedrine, Ephedrine and Pseudoephedrine in Pharmaceutical Preparation”. Asian Journal of Chemistry 21 (2):1145-54. https://asianpubs.org/index.php/ajchem/article/view/18802.