1. An introductory discussion is given in the following recent reviews: S. Datta, Electronic Transport in Mesoscopic Conductors, Cambridge University Press, 1995;
2. F. A. Buot, Phys. Rep. 234, 73 (1993);
3. C. W. J. Beenakker and H. van Houten, in Quantum transport in semiconductor nanostructures, eds. H. Ehrenreich and D. Turnbull (New York Academic Press, 1991).
4. N. F. Mott, Phil. Mag. 17, 1259 (1968);
5. N. F. Mott, Phil. Mag. 22 7 (1970).