1. C. Ambrosch-Draxl et al., Hyp. Int. to be published. K. Schwarz et al., Phys. Rev., submitted and this conference.
2. H. Chihara and N. Nakamura, Landolt-Börnstein New Series III 20a, Springer (1987).
3. H. Lütgemeier, Hyp. Int. to be published and this conference.
4. Bruker Almanac (1989).