1. Barth, W., Peters, C., Van de Ven, A.: Compact complex surfaces. Berlin Heidelberg New York: Springer 1984
2. Brieskorn, E.: Rationale Singularitäten komplexer Flächen, Invent. Math.4, 336–358 (1969)
3. Cartan, H.: Quotients of complex analytic spaces. In: Contribution to Function Theory, pp. 1–15, Bombay: Tata Institute 1960
4. Demazure, M.: Anneaux gradués normaux. In: Séminaire Demazure-Giraud-Teissier, Singularities des surfaces, Paris: École Polytechnique 1979
5. Lect. Notes Math.;I.V. Dolgachev,1982