International
Tables for Crystallography Volume A Spacegroup symmetry Edited by M. I. Aroyo © International Union of Crystallography 2016 
International Tables for Crystallography (2016). Vol. A, ch. 2.1, pp. 154155

For each of the two triclinic space groups, three elevations (along a, b and c) are given, in addition to the generalposition diagram (projected along c) at the lower right of the set, as illustrated in Fig. 2.1.3.1.
The diagrams represent a reduced cell of type II for which the three interaxial angles are nonacute, i.e. . For a cell of type I, all angles are acute, i.e. . For a discussion of the two types of reduced cells, see Section 3.1.3 .