1. C. P. Bean, Phys. Rev. Lett. 8, 250 (1962).
2. Y. B. Kim and P. W. Anderson, Rev. Mod. Phys. 36, 39 (1964).
3. K.-H. Muller, J. C. Macfarlane, and R. Driver, Rev. Mod. Phys. 158, 69 (1989).
4. Q.H. Lam, Y. Kim, and C. D. Jeffries, Phys. Rev. B 42, 4848 (1990).
5. A. A. Golubov, I. L. Serpuchenko, and A. V. Ustinov, Sov. Phys. JETP 67, 1256 (1988).