1. C. M. Varma, preprint.
2. A. Bill, V. Hizhnyakov, and E. Sigmund. unpublished.
3. M. E. Flatté,Phys. Rev. Lett. 70, 658 (1993).
4. A. Furrer, J. Mesot, P. Allenspach, U. Staub, F. Fauth, and M. Guillaume, inPhase Separation in Cuprate Superconductors, E. Sigmund and K. A. Müller, eds. (Springer-Verlag, Berlin, 1994).
5. W. Reichhardt,Neutron News 1, 20 (1990).