@article{ELMA_1968__23_140874,
     author = {H. Hadwiger},
     title = {Ungel\"oste {Probleme.}},
     journal = {Elemente der Mathematik},
     pages = {14--15},
     publisher = {mathdoc},
     volume = {23},
     year = {1968},
     url = {http://geodesic.mathdoc.fr/item/ELMA_1968__23_140874/}
}