@article{GDZPPN00207432X, title = {Ungel\"oste Probleme.}, journal = {Elemente der Mathematik}, volume = {13}, year = {1958}, pages = {85-86}, url = {http://dml.mathdoc.fr/item/GDZPPN00207432X} }
Hadwiger, H. Ungelöste Probleme.. Elemente der Mathematik, Tome 13 (1958) pp. 85-86. http://gdmltest.u-ga.fr/item/GDZPPN00207432X/