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2. S.M. Green, C. Jiang, Yu Mei, H.L. Luo, C. Politis: To be published
3. S.H. Liou, M. Hong, A.R. Rotan, J. Kwo, D.D. Bacon, C.H. Chen, R.C. Farrow, G.S. Grader: To be published
4. Y. Yamada et al.: Jpn. J. Appl. Phys. 26 (1987)
5. I. Apfelstedt, R. Flukiger, H. Kupfer, R. Meier-Hirmer, B. Obst, C. Politis, W. Schaner, F. Weiss, H. Wunl: To be published