1. For a review of the theories of spin waves in metals see: C. Herring: In Magnetism IV, ed. by G. T. Rado, H. Suhl ( Academic, New York 1966 )
2. A. K Rajagopal, H. Brooks, N. R. Ranganathan: Nuovo Cimento Suppl. 5, 807 (1967)
3. G. Barnea, G. Horwitz: J. Phys. C 6, 738 (1973)
4. H. A. Mook, R. M. Nicklow, E. D. Thompson, M. K. Wilkinson: J. Appl. Phys. 40, 1450 (1969)
5. E. D. Thompson, J. J. Myers: Phys. Rev. 153, 574 (1967)