@article{ELMA_1957__12_140671,
     author = {H. Hadwiger},
     title = {Ungel\"oste {Probleme.}},
     journal = {Elemente der Mathematik},
     pages = {109--110},
     publisher = {mathdoc},
     volume = {12},
     year = {1957},
     url = {http://geodesic.mathdoc.fr/item/ELMA_1957__12_140671/}
}