@article{ELMA_1972__27_141056,
     author = {H. Hadwiger},
     title = {Ungel\"oste {Probleme.}},
     journal = {Elemente der Mathematik},
     pages = {57--57},
     year = {1972},
     volume = {27},
     url = {http://geodesic.mathdoc.fr/item/ELMA_1972__27_141056/}
}