1. Bednorz, J.G., M�ller, K.A.: Z. Phys. B-Condensed Matter64, 189 (1986)
2. Bednorz, J.G., Takashige, M., M�ller, K.A.: Europhys. Lett.3(3), 379 (1987)
3. Uchida, S., Takagi, H., Kitizawa, K., Tanaka, S.: Jpn. J. Appl. Phys. Lett. (submitted for publication)
4. Takagi, H., Uchida, S., Kitazawa, K., Tanaka, S.: Jpn. J. Appl. Phys. Lett. (submitted for publication)
5. Chu, C.W., Hor, P.H., Meng, R.L., Gao, L., Huang, Z.J., Wang, Y.Q.: Phys. Rev. Lett.58, 405 (1987)