@article{GDZPPN002055538,
title = {Open Riemann Surfaces and Extremal Problems on Compact Subregions.},
journal = {Commentarii mathematici Helvetici},
volume = {24},
year = {1950},
pages = {100-134},
zbl = {0041.41102},
url = {http://dml.mathdoc.fr/item/GDZPPN002055538}
}
Ahlfors, Lars L. Open Riemann Surfaces and Extremal Problems on Compact Subregions.. Commentarii mathematici Helvetici, Tome 24 (1950) pp. 100-134. http://gdmltest.u-ga.fr/item/GDZPPN002055538/