1. Yu. I. Ravich, B. A. Efimova, and I. A. Smirnov, Investigation Methods of Semiconductors in Application to Lead Chalcogenidss PbTe, PbSe and PbS (Nauka, Moscow, 1968) [in Russian].
2. S. A. Nemov and Yu. I. Ravich, Phys. Usp. 41, 735 (1998).
3. G. Z. Bagieva, N. B. Mustafaev, S. Z. Dzhafarova, and G. D. Abdinova, Thans. Nat. Acad. Sci. Azerb., Phys.— Techn. Math. Sci. 30(2), 106 (2010).
4. G. Z. Bagieva, N. B. Mustafaev, G. D. Abdinova, and D. Sh. Abdinov, Semiconductors 45, 1391 (2011).
5. B. A. Akimov, A. V. Nikorich, L. I. Ryabova, and N. A. Shirokova, Sov. Phys. Semicond. 23, 636 (1989).