1. M.H. Brodsky (ed.):Amorphous Semiconductors, 2nd ed., Topics Appl. Phys., Vol. 36 ( Springer, Berlin, Heidelberg 1985 )
2. R.K. Bullough, P.J. Caudrey (eds.):Solitons, Topics Curr. Phys. Vol. 17 ( Springer, Berlin, Heidelberg 1980 )
3. W.E. Spear, P.G. Le Comber, A.J. Snell: Philos. Mag. B 38, 303 (1978)
4. G.A.N. Connell, R.A. Street:Handbook on Semiconductors, Vol.3 (North-Holland, Amsterdam 1980 ) p. 689
5. H. Mell: InProc. 5th/nt’! Conf. Amorphous and Liquid Semiconductors, ed. J. Stuke, W. Brenig ( Taylor and Francis, London 1974 ) p. 203