1. A.M.Danishevskii, A.A.Kastal'skii, S.M.Ryvkin, I.D.Yaroshetskii: Sov. Phys. JETP31, 292–295 (1970)
2. A.A.Grmberg: Sov. Phys. JETP31, 531–534 (1970)
3. P.M.Valov, B.S.Ryvkin, S.M.Ryvkin, I.D.Yaroshetskii: phys. stat. sol. (b)53, 65–70 (1972)
4. V.G.Agafonov, P.M.Valov, B.S.Ryvkin, I.D.Yaroshetskii: Sov. Phys. Semicond.7, 1540–45 (1974)
5. A.F.Gibson, M.F.Kimmit, A.C.Walker: Appl. Phys. Lett.17, 75–77 (1970)