1. See for example, N. Itoh, Adv. Phys. 31, 492 (1982) and
2. N. Itoh and K. Tanimura, Radiat. Eff. to be published and R. T. Williams, Semiconductors and Insulators 30, 251 (1978)
3. R. Engelman, Non-Radiative Decay of Ions and Molecules in Solids ( North-Holland, Amsterdam, 1979 )
4. A. M. Stoneham, Rep. Prog. Phys. 44, 1251 (1981)
5. E. I. Rashba, Excitons, eds. E. I Rashba and M. D. Sturge ( North-Holland, Amsterdam, 1982 ) p. 543