References
- Harker , H. 1967 . Phil. Mag. , 16 : 1193
- Harker , H. and Sherwood , P. M. A. 1973 . Phil. Mag. , 27 : 1241
- Ingram , D. J. E. 1958 . Free Radicals as Studied by Electron Spin Resonance , London : Butterworths .
- Mc Connell , H. M. and Robertson , R. E. 1957 . J. phys. Chem. , 61 : 1018
- Patrick , J. W. Third Conf. on Industrial Carbon and Graphite . pp. 91 London : Society Chemical Industries .
- Singer , L. S. Proc. 5th Carbon Conf. Vol. 2 , pp. 37 Oxford : Pergamon Press .