1. Y. Maeno, F. Nakamura, T. Suzuki, and T. Fujita,JJAP Ser. 7, 91 (1992).
2. Y. Maeno, N. Kakehi, Y. Tanaka, T. Tomita, F. Nakamura, and T. Fujita, inLattice Effects in High-Tc Superconductors, Y. Bar-Yam, T. Egami, J. Mustre-de-Leon, and A. R. Bishop, eds. (World Scientific, 1992), pp. 542?547.
3. M. K. Crawford, W. E. Farneth, R. L. Harlow, E. M. McCarron, R. Miao, H. Chou, and Q. Huang,ibid., pp. 531?541.
4. J. D. Axe,ibid., pp. 517?530.
5. A. R. Moodenbaugh, Y. Xu, M. Suenaga, T. J. Folkerts, and R. N. Shelton,Phys. Rev. B 38, 4596 (1988).