Erschienen in: IGOR O., Kulik, ed.. Quantum mesoscopic phenomena and mesoscopic devices in microelectronics : proceedings of the NATO Advanced Study Institute on Quantum Mesoscopic Phenomena and Mesoscopic Devices in Microelectronics, Ankara, Turkey, 13 - 25 June 1999. 2000, pp. 27-34. ISBN 0-7923-6626-3