@article{05191873,
title = {The densest geodesic ball packing by a type of Nil lattices.},
journal = {Beitr\"age zur Algebra und Geometrie},
volume = {48},
year = {2007},
pages = {383-397},
zbl = {1167.52016},
language = {en},
url = {http://dml.mathdoc.fr/item/05191873}
}
Szirmai, Jenő. The densest geodesic ball packing by a type of Nil lattices.. Beiträge zur Algebra und Geometrie, Tome 48 (2007) pp. 383-397. http://gdmltest.u-ga.fr/item/05191873/