| 1 | Beardon, A.F. 1983; The Geometry of Discrete Groups, Springer-Verlag, New York |
| 2 | Anderson, J.W. 2005; Hyperbolic Geometry, Springer-Verlag, 2.nd Edition, London |
| 3 | G.A. Jones and D.Singerman, Complex Functions: an algebraic and geometric viewpoint, Gambridge University Press,1987. |