1. A. Semet, L. C. Johnson and D. K. Mansfield, Int. J. IR. and MM. Waves,4, 231 (1983).
2. r. Behn, H. Do, I. Kjelberg, P. A. Krug, A. Salito, M. R. Siegrist and H. Weisen, Eighth Int. Conf. IR. and MM. Waves, digest 25.2 (1983).
3. J. S. Machuzak, P. Woskoboinikow and W. J. Mulligan, Eighth Int. Conf. IR. and MM. Waves, Digest W5. 1 (1983).
4. Y. Tsunawaki, M. Yamanaka, Y. Ichikawa, L.-D. Wu, I. Iwasaki, S. Okajima, A. Mitsuishi, t. Yamanaka and C. Yamanaka, Ninth Int. Conf. IR. and MM. Waves, Digest Th 7-4 p. 393 (1984).
5. T. Okada, S. Inoue, T. Ohga K. Muraoka and M. Akazaki, Ninth Int Conf. IR. and MM. Waves, Digest the 7-5 p. 395 (1984).