1. J. C. Wheatley,Rev. Mod. Phys. 47, 415 (1975).
2. J. C. Wheatley, inProgress in Low Temperature Physics, D. F. Brewer, ed. (North-Holland, Amsterdam, 1978), Vol. VIIa, p. 1.
3. D. M. Lee and R. C. Richardson, inThe Physics of Liquid and Solid Helium, Part II, K. H. Bennemann and J. B. Ketterson, ed. (Wiley, New York, 1978), p. 287.
4. W. P. Halperin,Physica 109B, 1596 (1982).
5. J. B. Ketterson, B. S. Shivaram, M. W. Meisel, B. K. Sarma, and W. P. Halperin,AIP Conf. Proc. 103, 288 (1983).