1. Ingram D.J.E. in: Free Radicals as Studied by Electron Spin Resonance, pp. 1–274. London: Butterworths 1958.
2. Prabhananda B.S., Shah S.J., Venkataraman B.: Indian J. Pure and Appl. Phys.10, 365 (1972)
3. Hüttermann J., Kappl R. in: Metal Ions in Biological Systems (Sigel H., ed.), vol. 22, pp. 1–80. New York: Dekker 1987.
4. Tsvetkov Y.D., Dikanov S.A. in: Metal Ions in Biological Systems (Sigel H., ed.), vol. 22, pp. 207–263, New York: Dekker 1987.
5. Fan C., Taylor H., Bank J., Scholes C.P.: J. Magn. Reson.76, 74 (1988)