Ara, Tabassum, and Khaliquz Zaman Khan. “Reaction of Dimethyl Sulphoxide and Trifluoroacetic Anhydride With 3-Nitro-4-Hydroxycoumarin”. Asian Journal of Chemistry 22, no. 5 (March 30, 2010): 3397–3403. Accessed July 18, 2024. https://asianpubs.org/index.php/ajchem/article/view/11561.