1. The Physics of Defects, R. Balian, M. Kleman and J. P. Poirier, eds. (North-Holland, Amsterdam, 1981).
2. J. S. Langer,Rev. Mod. Phys. 52:1 (1980).
3. J. D. Gunton, M. San Miguel, and P. S. Sahni, inPhase Transitions and Critical Phenomena, Vol. 8, edited by C. Domb and J. L. Lebowitz (Academic Press, London, 1983).
4. J. S. Langer,Physica 73:61 (1974).
5. A. Sur, J. L. Lebowitz, J. Marro, and M. H. Kalos,Phys. Rev. B 15:3014 (1977).