On subgroups of crystallographic Coxeter groups
A framework is presented based on color symmetry theory that will facilitate the determination of the subgroup structure of a crystallographic Coxeter group. It is shown that the method may be extended to characterize torsion-free subgroups. The approach is to treat these groups as groups of symmetries of tessellations in space by fundamental polyhedra.
Provido, E. D. B., De Las Peñas, M. A. N., & Felix, R. P. (2013). On subgroups of crystallographic Coxeter groups. Acta Crystallographica Section A: Foundations of Crystallography, 69(4), 445-451.