@article{GDZPPN002074702, title = {Ungel\"oste Probleme.}, journal = {Elemente der Mathematik}, volume = {15}, year = {1960}, pages = {130-131}, url = {http://dml.mathdoc.fr/item/GDZPPN002074702} }
Hadwiger, H. Ungelöste Probleme.. Elemente der Mathematik, Tome 15 (1960) pp. 130-131. http://gdmltest.u-ga.fr/item/GDZPPN002074702/