Voir la notice de l'article provenant de la source European Digital Mathematics Library
@article{ELMA_1970__25_140993, author = {Hugo Hadwiger}, title = {Ungel\"oste {Probleme.}}, journal = {Elemente der Mathematik}, pages = {135--135}, publisher = {mathdoc}, volume = {25}, year = {1970}, url = {http://geodesic.mathdoc.fr/item/ELMA_1970__25_140993/} }
Hugo Hadwiger. Ungelöste Probleme.. Elemente der Mathematik, Tome 25 (1970), p. 135. http://geodesic.mathdoc.fr/item/ELMA_1970__25_140993/