Bassi, Jacopo. “On $C^*$-Algebras Associated to Actions of Discrete Subgroups of $\operatorname{SL}(2,\mathbb{R})$ on the Punctured Plane”. MATHEMATICA SCANDINAVICA 126, no. 3 (September 3, 2020): 540–558. Accessed April 26, 2024. https://www.mscand.dk/article/view/120288.