Xu, Juncui, Jian-Hong Bi, Xiaobo Wang, and Yubiao Wang. “Simple Promethazine Method for Direct Spectrophotometry Determination of Nitrite in Water”. Asian Journal of Chemistry 21, no. 8 (March 30, 2010): 6483–6790. Accessed July 23, 2024. https://asianpubs.org/index.php/ajchem/article/view/12349.