@article{GDZPPN002396920, title = {On non-Euclidean crystallographic groups.}, journal = {Mathematische Zeitschrift}, volume = {93}, year = {1966}, pages = {87-102}, zbl = {0166.02602}, url = {http://dml.mathdoc.fr/item/GDZPPN002396920} }
Wilkie, H.C. On non-Euclidean crystallographic groups.. Mathematische Zeitschrift, Tome 93 (1966) pp. 87-102. http://gdmltest.u-ga.fr/item/GDZPPN002396920/