“…et al, 1994). Another way of looking at this problem for the cases of hexagonal (point group D6h), cubic (point group Oh) and trigonal (point group D3) crystal symmetry was proposed in the papers (Bukharova, Savyolova, 1985;Nikolaev, Savyolova, 1987;Ivanova, Savyolova, 1993). In the present paper it has been developed for the cases of triclinic and monoclinic crystal symmetry.…”