1. Kane, P.F. and Larrabee, G.R. (1974)Characterisation of Solid Surfaces, Plenum Press, New York.
2. Feuerbacher, B, Fitton, B. and Willis, R.F. (1978)Photoemission and the Electronic Properties of Surfaces, Wiley-Interscience, Chichester.
3. Joyner, R.W. (1977)Surface Sci.,63, 291.
4. Tricker, M.J. (1977) inSurface and Defect Properties of Solids, Vol. 6 (eds M.W. Roberts and J.M. Thomas), Specialist Periodical Reports, The Chemical Society, London, p. 106.
5. Jones, W, Thomas, J.M, Thorpe, R.K. and Tricker, M.J. (1978)Appl. Surf. Sci.,1, 388.