1. H. Kurreck, B. Kirtse, and W. Lubitz, Electron Nuclear Double Resonance of Radicals in Solution, VCH, Weinheim, 1988.
2. T.J. Stone and W.A. Waters, J. Chem. Soc., 1488 (1965).
3. N.M. Atherton and P.A. Henshaw, J. Chem. Soc. Perkin Trans. II 258 (1975).
4. See e.g., K. Herrmann, Fortschr. Chem. Org. Naturstoffe, 35, 73 (1978); E.E. Conn (Ed.), The Biochemistry of Plants. Volume 7. Secondary Plant Products Academic Press, New York, 1981; M. Luckner, Secondary Metabolism in Microorganisms, Plants, and Animals, (3rd Ed.), Springer-Verlag, Berlin, 1990.
5. See e.g., N.M. Atherton, Principles of Electron Spin Resonance, Ch. 9, Ellis Horwood, Chichester 1993.