@article{GDZPPN002059215, title = {Remarks on the Koebe Kreisnormierungsproblem.}, journal = {Commentarii mathematici Helvetici}, volume = {43}, year = {1968}, pages = {289-295}, zbl = {0172.37601}, url = {http://dml.mathdoc.fr/item/GDZPPN002059215} }
Sibner, Robert J. Remarks on the Koebe Kreisnormierungsproblem.. Commentarii mathematici Helvetici, Tome 43 (1968) pp. 289-295. http://gdmltest.u-ga.fr/item/GDZPPN002059215/