1. yu. V. Sharvin, Zh.Eksp.Teor. Fiz. 48, 984 (1965) [Sov. Phys. JETP 21, 655 (1965)]
2. V. S. Tsoi, Pis'ma Zh. Exp.Teor. Fiz. 19, 114 (1974) [JETP Lett. 19, 70 (1974)].
3. P. C. van Son, H. van Kempen, and P. Wyder, Phys. Rev. Lett. 58, 1567 (1987)
4. Physics and Technology of Submicron Structures, ed. by H. Heinrich, G. Bauer, and F. Kuchar (Springer, Berlin 1988); Nanostructure Physics and Fabrication, ed. be M. Reed and W. P. Kirk (Academic Press, New York, to be published)
5. H. van Houten, B. J. van Wees, J. E. Mooij, C. W. J. Beenakker, J. G. Williamson, and C. T. Foxon, Europhys. Lett. 5, 721 (1988).