Jin, Tong-Shou, Hong Xie, Yu-Peng Xue, and Tong-Shuang Li. 2010. “One-Pot Synthesis of Benzochromene Derivatives Catalyzed by KF-Al2O3 With Grinding”. Asian Journal of Chemistry 20 (7):5145-52. https://asianpubs.org/index.php/ajchem/article/view/12843.