1. Local properties of the singular sets of some Kleinian groups;Akaza;Tohoku Math. J.,1973
2. The Hausdorff dimension of singular sets of property discontinuous groups;Beardon;Amer. J. Math.,1966
3. Section on Hecke Groups;Beardon;Proc. London Math. Soc.,1968
4. Robert Brooks, The fundamental group and spectrum of the Laplacian, Comment. Math. Helv., to appear.
5. A lower bound for the lowest eigenvalues of the Laplacian;Cheeger,1970