@article{ELMA_1973__28_141111,
     author = {H. Hadwiger},
     title = {Ungel\"oste {Probleme.}},
     journal = {Elemente der Mathematik},
     pages = {97--97},
     publisher = {mathdoc},
     volume = {28},
     year = {1973},
     url = {http://geodesic.mathdoc.fr/item/ELMA_1973__28_141111/}
}