1. W. Ehrenstein, N. Mazur, and J. Scott, Nature (London) 442, 759 (2006).
2. A. V. Golubkov, E. V. Goncharova, V. P. Zhuze, G. M. Loginov, V. M. Sergeeva, and I. A. Smirnov, Physical Properties of Chalcogenides of Rare-Earth Elements (Nauka, Leningrad, 1973) [in Russian].
3. S. S. Aplesnin, Spin Liquid and Quantum Effects in Antiferromagnets (Palmarium, Saarbrücken, Germany, 2012).
4. S. S. Aplesnin, O. B. Romanova, M. V. Gorev, D. A. Velikanov, A. G. Gamzatov, and A. M. Aliev, J. Phys.: Condens. Matter 25, 025802 (2013).
5. S. S. Aplesnin, A. M. Har’kov, E. V. Eremin, O. B. Romanova, D. A. Balalev, V. V. Sokolov, and A. Yu. Pichugin, IEEE Trans. Magn. 47, 4413 (2011).