@article{GDZPPN002076292,
title = {Ungel\"oste Probleme.},
journal = {Elemente der Mathematik},
volume = {23},
year = {1968},
pages = {14-15},
url = {http://dml.mathdoc.fr/item/GDZPPN002076292}
}
Hadwiger, H. Ungelöste Probleme.. Elemente der Mathematik, Tome 23 (1968) pp. 14-15. http://gdmltest.u-ga.fr/item/GDZPPN002076292/