1. N. F. Mott andH. Jones:Metals and Alloys (Oxford, 1936).
2. L. F. Bates andS. J. Leach:Proc. Phys. Soc.,69 B, 997 (1956);J. A. Catterall:Phil. Mag.,2, 491 (1957).
3. E. Vogt andR. Lingelbach: private communication.
4. C. J. Smithells:Metals Reference Book (London, 1949).
5. The reasoning put forward here is only valid for the shearing of a Brillouin zone without change of volume. The situation is more complicated for a dilatation. Cf.H. Jones:Proc. Roy. Soc., A147, 400 (1934);J. B. Goodenough:Phys. Rev.,89, 282 (1953).