1. Babka, J., D. Doskocilova, H. Pivcova, Z. Ruzicka, B. Schneider, Apparatus for the Measurement of Proton Magnetic Resonance Spectra under Magic Angle Rotation, Proceedings of the XVIth Congress A.M.P.E.R.E. (Bucharest 1970).
2. Andrew, E. R., Progress in Nuclear Magnetic Resonance Spectroscopy (Oxford 1971).
3. Cunningham, A. C., S. M. Day, Phys. Rev. 152, 287 (1966).
4. Kessemeier, H., R. E. Norberg, Phys. Rev. 155, 321 (1967).
5. Lowe, I. J., Phys. Rev. Letters 2, 285 (1959).