1. See, e.g., articles in Physics of Sliding Friction , B.N.J. Persson and E. Tosatti, eds., Kluwer: Dordrecht, 1996.
2. J. Gao, W.D. Luedtke and U. Landman in Physics of Sliding Friction , B.N.J. Persson and E. Tosatti, eds., Kluwer: Dordrecht, 1996.
3. J. Krim, D.H. Solina and R. Chiarello, Phys. Rev. Letters 66 181 (1991).
4. J.B. Sokoloff, Phys. Rev. B42 760 (1990).
5. H. Yoshizawa and J. Israelachvili, J. Phys. Chem. 97 11300 (1993).