1. Exellent reviews of the theoretical and some of the experimental work which was done on excitons until 1962 is given by R. S. Knox: Theory of Excitons, Suppl. 5 of Solid State Physics (H. Ehrenreich, F. Seitz, and D. Turnbull, eds.) Academic Press, New York 1963). By R. J. Elliott, Theory of Excitons I in “Polarons and Excitons” (C. G. Kuper and G. D. Whitfield, eds.) p. 269. Plenum Press, New York 1963 and by H. Haken, Theory of Excitons II in “Polarons and Excitons” (C. G. Kuper and G. D. Whitfield, eds.) p. 295. Plenum Press, New York 1963.
2. J. O. Dimmock reviews the situation for III–V-compounds in “Semiconductors, and Semimetals”, Vol. 3 (R. K. Willardson and A. C. Beer, eds.) p. 259. Academic Press, New York 1967.
3. E. J. Johnson and H. Y. Fan, Phys. Rev. 139, A 1991 (1965).
4. A. Baldereschi and N. O. Lipari, Phys. Rev. Lett 25, 373 (1970) and Phys. Rev. B3, 439 (1971).
5. Altarelli and N. O. Lipari, Phys. Rev. B7, 3798 (1973) and ibid. Altarelli and N. O. Lipari, Phys. Rev. B8, 4046 (E) (1973).