A. TARIQ, S. I. A. SHAH, and A. ALI. “Ratios of the Ring Class Numbers and Class Numbers of a Real Quadratic Field”. Sindh University Research Journal - SURJ (Science Series), Vol. 49, no. 1, Feb. 2021, https://sujo.usindh.edu.pk/index.php/SURJ/article/view/3185.