@article{GDZPPN002074451, title = {Ungel\"oste Probleme.}, journal = {Elemente der Mathematik}, volume = {14}, year = {1959}, pages = {60-61}, url = {http://dml.mathdoc.fr/item/GDZPPN002074451} }
Hadwiger, H. Ungelöste Probleme.. Elemente der Mathematik, Tome 14 (1959) pp. 60-61. http://gdmltest.u-ga.fr/item/GDZPPN002074451/