JIN, TONG-SHOU, NA QI, MENG LI, LI-SHA HAN, LI-BIN LIU, and TONG-SHUANG LI. 2010. “One-Pot Synthesis of 9-Aryl-1,8-Dioxo-1,2,3,4,6,7,8- Octahydroxanthenes Catalyzed by P-Dodecylbenzene Sulfonic Acid in Aqueous Media”. Asian Journal of Chemistry 19 (5):3803-9. https://asianpubs.org/index.php/ajchem/article/view/13282.