1. Altarelli M 1983a Physica 117B + 118B 747,1983b Phys Rev B28 842,1986 in “Heterojunctions and Semiconductor Superlattices” Eds G Allan et al ( Springer, Berlin ) p12.
2. Burt M G 1987 Semicond Sci Technol 2 460 and 701 1988a to appear in Semicond Sci Technol 1988b to be submitted for publication.
3. Herbert D C and Gell M A 1987 Phys Rev B35 9591.
4. Kane E O 1966 in “Semiconductors in Semimetals” 1 R K Willardson and A C Beer Eds ( New York, Academic ) p75.
5. Luttinger J M and Kohn W 1955 Phys Rev 97 869.