International
Tables for Crystallography Volume D Physical properties of crystals Edited by A. Authier © International Union of Crystallography 2013 
International Tables for Crystallography (2013). Vol. D, ch. 3.4, p. 507
Figure 3.4.3.2^{a}Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, CZ18221 Prague 8, Czech Republic, and ^{b}Department of Mathematics and Didactics of Mathematics, Technical University of Liberec, Hálkova 6, 461 17 Liberec 1, Czech Republic 

Figure 3.4.3.2
Nontransposable domain pairs. (a) The parent phase with symmetry is represented by a dotted hexagon and the three ferroelastic singledomain states with symmetry are depicted as drastically squeezed hexagons. (b) Domain pair and transposed domain pair . There exists no operation from the group that would exchange domain states and , i.e. that would transform one domain pair into a transposed domain pair. 