1. H.R. Zeller, Festkorperproblerne, 1973, 13, 31.;
2. H.R. Zeller, ‘One Dimensional Conductors’ Ed. H.G. Schuster, Springer-Verlag 1975.
3. D.J. Wood and A.E. Underhill, N.Y. Acad. Sci., in press.
4. K. Krogmann, Z. Anorg. Allg. Chem., 1968, 358, 97.
5. A.J. Schultz, A.E. Underhill and J.M. Williams, Inorg. Chem., 1978, 17, 1313.