1. Present address: Research Center for Dielectric and Advanced Matter Physics, Pusan National University, 30 Jangjun-Dong, Kumjeong-Ku, Pusan 609-735, South Korea.
2. Present address: Center for Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
3. Present address: Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
4. Deceased.
5. Birgeneau, R.J. and Shirane, G. (1989), in Physical Properties of High Temperature Superconductors I, ed. D.M. Ginsberg, World Scientific, Singapore, pp. 151–211.