1. V. A. Kizel’ and V. I. Burkov, Gyrotropy of Crystals (Nauka, Moscow, 1980) [in Russian].
2. V. I. Burkov, Neorg. Mater. 30(1), 12 (1994).
3. F. S. Richardson, J. Less-Common Met. 149, 151 (1989).
4. A. A. Kaminskii, B. V. Mill’, and S. É. Sarkisov, Physics and Spectroscopy of Laser Crystals (Nauka, Moscow, 1986) [in Russian].
5. K. Kaldybaev, A. F. Konstantinova, and Z. B. Perekalina, Gyrotropy of Uniaxial Absorbing Crystals (In-t otsial’no-ekonomicheskikh i proizvodstvenno-eko-logicheskikh problem investirovaniya, Moscow, 2000) [in Russian].