@article{GDZPPN002077027, title = {Ungel\"oste Probleme.}, journal = {Elemente der Mathematik}, volume = {24}, year = {1969}, pages = {126-128}, url = {http://dml.mathdoc.fr/item/GDZPPN002077027} }
Hadwiger, H. Ungelöste Probleme.. Elemente der Mathematik, Tome 24 (1969) pp. 126-128. http://gdmltest.u-ga.fr/item/GDZPPN002077027/