1. Isoya J., Kanda H., Uchida Y.: Phys. Rev.B42, 9843–9842 (1990); Strong, H.M.: U.S. Patent No. 4 030 066 (1977)
2. Smith W.V., Sorokin P.P., Gelles I.L., Lasher G.J.: Phys. Rev.115, 1546–1552 (1959)
3. Cox A., Newton M.E., Baker J.M.: J. Phys.: Condens. Matter6, 551–563 (1994)
4. van Wyk J.A., Loubser J.H.N., Newton M.E., Baker J.M.: J. Phys.: Condens. Matter4, 2651–2662 (1992)
5. Morton J.R., Preston K.F.: J. Magn. Reson.30, 577–582, (1978)