@article{CMH_1956__30_139117,
     author = {H. Wittich},
     title = {\"Uber eine {Klasse} {Riemannscher} {Fl\"achen.}},
     journal = {Commentarii mathematici Helvetici},
     pages = {116--123},
     publisher = {mathdoc},
     volume = {30},
     year = {1956},
     language = {de},
     url = {http://geodesic.mathdoc.fr/item/CMH_1956__30_139117/}
}