@article{GDZPPN00205096X, title = {Ueber Riemannsche Fl\"achen.}, journal = {Commentarii mathematici Helvetici}, volume = {2}, year = {1930}, pages = {284-293}, zbl = {56.0987.03}, url = {http://dml.mathdoc.fr/item/GDZPPN00205096X} }
Speiser, A. Ueber Riemannsche Flächen.. Commentarii mathematici Helvetici, Tome 2 (1930) pp. 284-293. http://gdmltest.u-ga.fr/item/GDZPPN00205096X/