@article{VM_2002_4_4_a3,
     author = {Raymond F. Tennant},
     title = {Subgroup {Lattices} for {Crystallographic} {Groups}},
     journal = {Visual Mathematics},
     year = {2002},
     volume = {4},
     number = {4},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/VM_2002_4_4_a3/}
}