The procedure of Backhouse for the determination of a complete set of inequivalent factor systems of the symmorphic Shubnikov space groups of type I is generalized for all Shubnikov space groups of types I and 111. The results are used to obtain a method for the construction of a set of inequivalent factor systems of the Shubnikov space groups of types I1 and IV.
van den Broek, P. M. (1977). On the factor systems of the Shubnikov space groups. Journal of physics A: mathematical and general, 10(5), 649-658. [10.1088/0305-4470/10/5/019]. https://doi.org/10.1088/0305-4470/10/5/019