@article{ELMA_1970__25_140993,
     author = {Hugo Hadwiger},
     title = {Ungel\"oste {Probleme.}},
     journal = {Elemente der Mathematik},
     pages = {135--135},
     publisher = {mathdoc},
     volume = {25},
     year = {1970},
     url = {http://geodesic.mathdoc.fr/item/ELMA_1970__25_140993/}
}