1. E.Burstein, S.Perkowitz, M.H.Brodsky: J. Phys. (Paris) C4, 78–83 (1968)
2. R.T.Bate, D.L.Carter, J.S.Wrobel: Phys. Rev. Lett.25, 159–162 (1970)
3. G.S.Pawley, W.Cochran, R.A.Cowley, G.Dolling: Phys. Rev. Lett.17, 753–755 (1966)
4. R.T.Bate, D.L.Carter, J.S.Wrobel:Proc. 10. Intern. Conf. Phys. of Semiconductors, Cambridge/MA (1970), ed. by S.P.Keller, J.C.Hensel, F.Stern, (USAEC Division of Technical Information Extension, Oak Ridge, TE 1970), pp. 125–129
5. G.M.T.Foley, D.N.Langenberg: Phys. Rev. B15, 4830–4849 (1976)