1. J. Rossat-Mignod in “Methods of Experimental Physics.” Vol. 23C Academic Press, New York. 1978;
2. see L. Asch, Hyperfine Interactions64 (1990), 351 and references given therein;
3. M. Hagen et al. Phys. Rev.B37 (1988), 1846;
4. O. Vogt, private communication;
5. G. Lander, private communication and 23e Journée des Actinides (1993);