1. N. Kurti and F. Simon, Pric. Roy. Soc. (London) A151 (1935) 610.
2. R. H. Borcherts and A. H. Silver, Bulletin of the Amer. Phys. Soc. 13 (1968) 379. To the knowledge of the authors, the detailed results of this work have not been published.
3. I. A. Popov and N. V. Shiryaeva, Russ. J. Inorg. Chem. 6 (1961) 1184.
4. R. P. Elliott, ?Constitution of Binary Alloys?, First Supplement (McGraw-Hill, New York, 1965) p. 253.
5. B. B. Argent and R. E. Goosey, private communication to G. L. Miller, ?Tantalum and Niobium? (Academic Press, New York, 1959) pp. 566?67.