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. 534
Figure 3.4.4.4^{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 3.4.4.4
Microscopic structure of two domain states and two parallel mutually reversed domain walls in the phase of quartz. The lefthand vertical dotted line represents the domain wall , the righthand line is the reversed domain wall . To the left of the lefthand line and to the right of the righthand line are domains with domain state , the domain between the lines has domain state . For more details see text. Courtesy of M. Calleja, University of Cambridge. 