1. H. Nomura, K. Takahisa, K. Koyama and T. Sakai, Cryogenics 17: 471 (1977).
2. P. Turowski, in Proceedings of the 6th Intern. Conf. on Magnet Technology (MT-6), Alfa, Bratislava (1978), p. 648.
3. M.W. Sinclair, O. Tsukamoto and Y. Iwasa, IEEE Trans. Magn. MAG-17: 1064 (1981).
4. Tsukamoto, M.F. Steinhoff and Y. Iwasa, in Proc. of 9t Symp. on Eng. Probl. of Fusion Research, IEEE Pub. No 81CH1715–2 NPS, IEEE, New York (1981), p. 309.
5. M. Pappe, IEEE Trans. Magn. MAG-17: 2082 (1981).