@article{MAN_1928__98_159220,
     author = {I. Gawehn},
     title = {\"Uber unberandete 2-dimensionale {Mannigfaltigkeiten}},
     journal = {Mathematische Annalen},
     pages = {321--354},
     publisher = {mathdoc},
     volume = {98},
     year = {1928},
     zbl = {53.0556.04},
     url = {http://geodesic.mathdoc.fr/item/MAN_1928__98_159220/}
}