Geometric finiteness and uniqueness for Kleinian groups with circle packing limit sets. Linda Keen, Bernard Maskit (1993) Journal für die reine und angewandte Mathematik
Geometric intersection numbers on a five-punctured sphere. Chiang, Yungyen (2001) Annales Academiae Scientiarum Fennicae. Mathematica
Group Completions and Limit Sets of Kleinian Groups. William J. Floyd (1980) Inventiones mathematicae