Qin, X.-Y., Jin, T.-S., Zhou, Z.-X., & Li, T.-S. (2010). Silica Sulfuric Acid: An Efficient and Versatile Catalyst for One-Pot Synthesis of Substituted 5-Oxo-1,4,5,6,7,8-hexahydroquinoline Derivatives. Asian Journal of Chemistry, 22(2), 1179–1182. Retrieved from https://asianpubs.org/index.php/ajchem/article/view/11247