1. A. Abragam, B. Bleaney: Electron Paramagnetic Resonance of Transition Ions (Clarendon, Oxford 1970)
2. G.E. Pake, T.L. Estle: The Physical Principles of Electron Paramagnetic Resonance, 2nd ed. (Benjamin, New York 1973)
3. W. Känzig, M.H. Cohen: Phys. Rev. Lett. 3, 509 (1959)
4. H. Seidel, H.C. Wolf: ”ESR and ENDOR Spectroscopy of Color Centers in Alkali Halide Crystals”, in Physics of Color Centers, ed. by W.B. Fowler (Academic, New York 1968)
5. H.R. Zeller, W. Känzig: Helv. Phys. Acta. 40, 845 (1967)