@article{JRAM_1927__156_149602,
     author = {L. Berwald},
     title = {\"Uber zweidimensionale allgemeine metrische {R\"aume.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {191--222},
     publisher = {mathdoc},
     volume = {156},
     year = {1927},
     language = {de},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1927__156_149602/}
}