International
Tables for Crystallography Volume B Reciprocal space Edited by U. Shmueli © International Union of Crystallography 2010 
International Tables for Crystallography (2010). Vol. B, ch. 2.5, p. 350
Figure 2.5.3.20
M. Tanaka^{f}


Figure 2.5.3.20
(a) Mirror symmetry of modulation waves () τ_{4} = 0. (b) Glide symmetry of modulation waves () τ_{4} = ½. The wave number vector of modulation is k_{3}c*. 