Zou, Deqing, Yan Zou, and Yaling Yang. “Determination of Morphine in Urine by HPLC Using Ion-Pair Extraction”. Asian Journal of Chemistry 25, no. 5 (December 10, 2012): 2469–2473. Accessed July 22, 2024. https://asianpubs.org/index.php/ajchem/article/view/25_5_26.