@article{GDZPPN002283212, title = {Das Problem der 13 Kugeln.}, journal = {Mathematische Annalen}, volume = {125}, year = {1952}, pages = {325-334}, zbl = {0050.16701}, url = {http://dml.mathdoc.fr/item/GDZPPN002283212} }
Waerden van der, B.L.; Schütte, K. Das Problem der 13 Kugeln.. Mathematische Annalen, Tome 125 (1952) pp. 325-334. http://gdmltest.u-ga.fr/item/GDZPPN002283212/