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2. Hagedorn, F.B.: AIP Conf. Proc.5, 72 (1972)
3. Schlömann, E.: AIP Conf. Proc.5, 160 (1972)
4. Schryer, N.L., Walker, L.R.: J. Appl. Phys.45, 5406 (1974)
5. Slonczewski, J.C.: AIP Conf. Proc.5, 170 (1972)