1. Andrew, E.R. and Bradbury, A. and Eades, R.G. (1958) Nature, Lond., 182, pp. 1659 - 1659. Lowe, I. J., 1959, Phys. Rev. Lett., 2, 285.
2. Schaefer, J. and Stejskal, E.O. (1976) J. Am. chem. Soc., 98, pp. 1031 - 1031.
3. Andrew, E.R. and Hinshaw, W.S. and Tiffen, R.S. (1973) Phys. Lett., A, 46, pp. 57 - 57. 1974, J. magn. Reson., 15, 191.
4. Stejskal, E.O. and Schaefer, J. and McKay, R.A. (1977) J. magn. Reson., 25, pp. 569 - 569.
5. Lippmaa, E. and Alla, M. and Turherm, T.(1976). . Proceedings of the 19th Congress at Ampère . In [ pp. 113 - 113] . .