1. A. J. F. Boyle and H. E. Hall, Rept. Progr. Phys. 25: 441 (1962).
2. A. Abragam and R. V. Pound, Phys. Rev. 92: 943 (1953).
3. A. Abragam, Principles of Nuclear Magnetism (Oxford University Press, London, 1961 ).
4. A. Abragam and M. H. L. Pryce, Proc. Roy. Soc. (London)
A205: 135 (1951).
5. J. A. Pople, W. G. Schneider, and H. J. Bernstein, High-Resolution Nuclear Magnetic Resonance (McGraw-Hill Book Company, New York, 1959 ).