Some special $2$-generator Kleinian groups

Bernard Maskit
1989 Proceedings of the American Mathematical Society  
We explore the following question. Let G be the subgroup of PSL(2, C) generated by the elements A and B , where A has two fixed points, and B maps one fixed point of A onto the other; when is G discrete?
doi:10.1090/s0002-9939-1989-0937850-4 fatcat:uhrx6lgd7vcrfmpi7hdufjuo5e