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. 517
Figure 3.4.3.5^{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 3.4.3.5
Two ways of constructing a ferroelastic domain twin. (a) Formation of ferroelastic singledomain states from the parent phase state and then rotating away these singledomain states through an angle about the domainpair axis H so that disoriented ferroelastic domain states and meet along one of two perpendicular planes of equal deformation p or . (b) Formation of a ferroelastic twin from one ferroelastic domain state by a simple shear deformation with a shear angle (obliquity) . For more details see the text. 