1. C. Albanese,J. Stat. Phys., to appear.
2. J. Glimm,Commun. Math. Phys. 5:343?386 (1967).
3. C. Albanese,Commun. Math. Phys. 120:97 (1988).
4. T. Kato,Perturbation Theory for Linear Operators (Springer, Berlin, 1966).
5. N. Mott,Metal-Insulator Transitions (Taylor & Francis, London, 1966).