1. W. M�ller, R. Schenkel, H. E. Schmidt, J. C. Spirlet, D. L. McElroy, R. O. A. Hall, and M. J. Mortimer, J. Low Temp. Phys. 30, 561 (1978).
2. D. B. McWhan, B. B. Cunningham, and J. C. Wallmann, J. Inorg. Nucl. Chem. 24, 1025 (1962).
3. D. R. Stephens, H. D. Stromberg, and E. M. Lilley, J. Phys. Chem. Solids 29, 815 (1968).
4. R. O. A. Hall, D. L. McElroy, M. J. Mortimer, W. M�ller, and J. C. Spirlet, in Transplutonium Elements 1976, W. M�ller and R. Lindner, eds. (North-Holland, Amsterdam), p. 139.
5. J. W. Ward and H. H. Hill, in Heavy Element Properties, W. M�ller and H. Blank, eds. (North-Holland, Amsterdam, 1976), p. 65.