@article{GDZPPN002346745, title = {Discrete Subgroups of the Lorentz Group.}, journal = {Mathematica Scandinavica}, volume = {11}, year = {1962}, pages = {85-107}, zbl = {0118.03902}, url = {http://dml.mathdoc.fr/item/GDZPPN002346745} }
Greenberg, Leon. Discrete Subgroups of the Lorentz Group.. Mathematica Scandinavica, Tome 11 (1962) pp. 85-107. http://gdmltest.u-ga.fr/item/GDZPPN002346745/