Bassi, J. 2020. On $C^*$-algebras associated to actions of discrete subgroups of $\operatorname{SL}(2,\mathbb{R})$ on the punctured plane. MATHEMATICA SCANDINAVICA. 126, 3 (Sep. 2020), 540–558. DOI:https://doi.org/10.7146/math.scand.a-120288.