@article{ELMA_1961__16_140725,
     author = {H. Hadwiger},
     title = {Ungel\"oste {Probleme.}},
     journal = {Elemente der Mathematik},
     pages = {30--31},
     publisher = {mathdoc},
     volume = {16},
     year = {1961},
     url = {http://geodesic.mathdoc.fr/item/ELMA_1961__16_140725/}
}