1. Zh. I. Alferov, Yu. V. Zhilyaev, and Yu. V. Shmartsev, Fiz. Tekh. Poluprovodn. 5, 196 (1971) [Sov. Phys. Semicond. 5, 174 (1971)].
2. A. Segmuller and A. E. Blakeslee, J. Appl. Crystallogr. 6, 19 (1973).
3. A. Ya. Shik, Fiz. Tekh. Poluprovodn. 8, 1841 (1974) [Sov. Phys. Semicond. 8, 1195 (1974)].
4. Zh. I. Alferov, in Science and Humanity, Intern. Yearbook (Znanie, Moscow, 1976) [in Russian].
5. R. A. Suris, Élektron. Prom., No. 5, 52 (1977).