1. Armstrong, M.A.: The fundamental group of the orbit space of a discontinuous group. Proc. Cam. Phil. Soc.64 (1968) 299–301
2. Ash, A., Mumford, D., Rapoport, M., Tai, Y.: Smooth Compactifications of Locally Symmetric Varieties. Math. Sci. Press, Brookline, Mass., 1975
3. Barth, W., Nieto, I.: Abelian surfaces of type (1,3) and quartic surfaces with 16 skew lines. J. Alg. Geom.3 (1994) 173–222
4. Beauville, A.: A Calabi-Yau threefold with non-abelian fundamental group. Preprint, 1995
5. Bruce, J.W., Giblin, P.: Curves and Singularities. Cambridge University Press, Cambridge, 1992