On some discrete subgroups of the Lorentz group

Some discrete subgroups of the Lorentz group are found using Fedorov's parametrization by means of complex vector-parameter. It is shown that the discrete subgroup of the Lorentz group, which have not fixed points, are contained in boosts along a spatial direction for time-like and space-like vectors and are discrete subgroups of the group SO(1,1), whereas discrete subgroups of isotropic vector are subgroups of SO(1,1)\times E(1,1).