@article{MZ_1922__13_167688,
     author = {Liebmann. H.},
     title = {Zwei charakteristische {Eigenschaften} der {Fl\"achen} konstanten {Kr\"ummungsma{\ss}es.}},
     journal = {Mathematische Zeitschrift},
     pages = {10--17},
     publisher = {mathdoc},
     volume = {13},
     year = {1922},
     zbl = {48.0807.01},
     url = {http://geodesic.mathdoc.fr/item/MZ_1922__13_167688/}
}