International
Tables for Crystallography Volume A Spacegroup symmetry Edited by Th. Hahn © International Union of Crystallography 2006 
International Tables for Crystallography (2006). Vol. A. ch. 1.4, p. 9
Section 1.4.5. Symmetry axes normal to the plane of projection and symmetry points in the plane of the figure^{a}Institut für Kristallographie, RheinischWestfälische Technische Hochschule, Aachen, Germany 
1.4.5. Symmetry axes normal to the plane of projection and symmetry points in the plane of the figure
^{†}
Notes on the `heights' h of symmetry points , , and :
