@article{GDZPPN002075172, title = {Ungel\"oste Probleme.}, journal = {Elemente der Mathematik}, volume = {18}, year = {1963}, pages = {29-31}, url = {http://dml.mathdoc.fr/item/GDZPPN002075172} }
Hadwiger, H. Ungelöste Probleme.. Elemente der Mathematik, Tome 18 (1963) pp. 29-31. http://gdmltest.u-ga.fr/item/GDZPPN002075172/