1. M N Hack and M Hamermesh, Nuovo Cimento 19 (1961) 546.
2. E Matthias in “Hyperfine Structure and Nuclear Radiations” (eds. E Matthias and D A Shirley) North-Holland Amsterdam (1968) p.815.
3. E Recknagel in “Hyperfine Interactions in Excited Nuclei” (eds. G Goldring and R Kalish) Gordon & Breach (1971) p.291.
4. N J Stone, Hyperfine Interactions 2 (1976) 45.
5. E Matthias and R J Holliday, Phys.Rev. Lett. 17 (1966) 897.