1. For a review see: E. Poels and V. Ponec, Catalysis 6 (1983) 196.
2. M. Bowker, P.D.A. Pudney and C. Barnes, J. Vac. Sci. Tech. A8 (1990) 816.
3. M. Bowker and R.J. Madix, Surf. Sci. 116 (1982) 549.
4. P.D.A. Pudney, S. Francis, R.W. Joyner and M. Bowker, J. Catal., accepted.
5. M. Bowker, Q. Guo and R.W. Joyner, Surf. Sci., in press.