1. A. V. Shubnikov and V. A. Koptsik, Symmetry in Science and Art (Nauka, Moscow, 1972) [in Russian].
2. A. M. Zamorzaev, Theory of Simple and Multiple Antisymmetry (Shtiintsa, Chisinau, 1976) [in Russian].
3. A. M. Zamorzaev and A. F. Palistrant, Theory of Discrete Symmetry Groups (Izd-vo KGU, Kishinev, 1977) [in Russian].
4. E. S. Fedorov, Symmetry and Structure of Crystals. Fundamental Works (Akad. Nauk SSSR, Moscow, 1949) [in Russian], p. 109; Zap. Mineral. O-va, Ser. 2 28, 1 (1891) (original study).
5. E. S. Fedorov, Principles of the Theory of Figures (Izd-vo AN SSSR, Moscow, 1953) [in Russian]; Zap. Mineral. O-va, Ser. 2 21, 1 (1885) (original study).