1. Imry, Y., Ma, S.K.: Phys. Rev. Lett.35, 1399 (1975)
2. For reviews, see Imry, Y.: J. Stat. Phys.34, 849 (1984) and Refs. [3?6]
3. Stinchcombe, R.B.: In: Phase Transitions and Critical Phenomena, vol. 7, Domb, C., Lebowitz J.L. (eds) London: Academic Press 1983 p. 150
4. Villain, J.: in: Scaling Phenomena in Disordered Systems p. 150 Pynn, R., Skjeltorp A. (eds.) New York: Plenum Press 1985
5. Nattermann, T., Villain, J.: Phase Transitions11, 5 (1988)