Diameter problems for univalent functions with quasiconformal extension. Deiermann, Paul (1993) International Journal of Mathematics and Mathematical Sciences
Die Koeffizientenkörper schlichter Trinome. Volker Kasten, Gerald Schmieder (1980) Mathematische Zeitschrift
Domains with convex hyperbolic radius. Kovalev, L.V. (2001) Acta Mathematica Universitatis Comenianae. New Series