1. Ando, T., Fowler, A.B., Stern, F. (1982), Rev. of Modern Physics 54, 437.
2. Bangert, E., von Klitzing, K., Landwehr, G. (1974), Proc. 12th Int. Conf. on the Physics of Semiconductors, Stuttgart, M. Pilkuhn Ed., Teubner Verlag, p. 714.
3. Bangert, E., Landwehr, G. (1985), Superlattices and Microstructures 1, 363.
4. Bangert, E., Landwehr, G. (1986), Surface Science 170, 593.
5. Bauer, G.E.W., Ando, T. (1988), Phys. Rev. B37, 3130.