1. H. Hertz, “Hertz's Miscellaneous Papers” (Macmillan, London, 1896) Ch. 5 and 6.
2. M. T. Huber, Ann. Physik
14 (1904) 153.
3. G. Lundberg and H. Sjövall, Publikation no 4, Chalmers Unilversity of Technology, Göteborg (1958).
4. K. Zeng, K. Breder and D. J. Rowcliffe, submitted (1991).
5. Idem., ibid. (1991).