1. C. Poole, The Technique of EPR Spectroscopy (Mir, Moscow, 1970), 557 pp. [Russian translation]
2. C. Slichter, Principles of Magnetic Resonance, 3rd edn. (Springer, New York, 1990), 655 pp.
3. Handbuch der Physik;S. Metfessel,1968
4. I.I. Geru, I.G. Lupea, K.G. Nikiforov, S.I. Radautsan, V.E. Tezlevan, Fiz. Tverd. Tela 20, 1534–1535 (1978)
5. U. Kuhn, F. Lüty, Solid State Commun. 3(2), 31–33 (1965)