1. J. H. Cardy,J. Phys. A 16: 3617 (1983).
2. See, e.g., W. Panofsky and M. Phillips,Classical Electricity and Magnetism, (Addison-Wesley, Cambridge, 1955), Section 4.11.
3. I. Syozi, inPhase Transitions and Critical Phenomena, C. Domb and M. S. Green, eds. (Academic Press, London, 1972), Vol. 1, p. 270.
4. H. J. Hilhorst, M. Schick, and J. M. J. van Leeuwen,Phys. Rev. B 19:2749 (1979).
5. H. J. Hilhorst and J. M. J. van Leeuwen,Phys. Rev. Lett. 47:1188 (1981).