@article{MAN_1869__1_156425,
     author = {E. Beltrami},
     title = {Zur {Theorie} des {Kr\"ummungsmaasses,} {Von} {E.} {Beltrami} in {Bologna.}},
     journal = {Mathematische Annalen},
     pages = {575--582},
     publisher = {mathdoc},
     volume = {1},
     year = {1869},
     language = {de},
     url = {http://geodesic.mathdoc.fr/item/MAN_1869__1_156425/}
}