1. S. Nakai, K. Mima, Rep. Prog. Phys. 67, 321 (2004)
2. R. Pohl, H. Daniel, F.J. Hartmann, P. Hauser, F. Kottmann, V.E. Markushin, M. Mühlbauer, C. Petitjean, W. Schott, D. Taqqu, P. Wojciechowski-Grosshauser, Phys. Rev. Lett. 97, 193402 (2006)
3. R. Pohl, H. Daniel, F.J. Hartmann, P. Hauser, Y.W. Liu, F. Kottmann, C. Maierl, V.E. Markushin, M. Mühlbauer, C. Petitjean, W. Schott, D. Taqqu, Hyperfine Interact. 35, 138 (2001); F. Kottmann et al., Hyperfine Interact. 138, 55 (2001)
4. K. Nagamine, L. Ponomarev, Nucl. Phys. A 721, 863c (2003); L. Ponomarev, Contemp. Phys. 31, 219 (1990)
5. A.K. Bhatia, R.J. Drachman, Can. J. Phys. 79, 1149 (2001)