1. E. Kim, M.H.W. Chan, Nature 427, 225 (2004)
2. E. Kim, M.H.W. Chan, Science 305, 1941 (2004)
3. A.S.C. Rittner, J.D. Reppy, Phys. Rev. Lett. 101, 155301 (2008)
4. D. Galli, L. Reatto, J. Phys. Soc. Jpn. 77, 111010 (2008), see this review article and references therein
5. E. Kim, J.S. Xia, J.T. West, X. Lin, A.C. Clark, M.H.W. Chan, Phys. Rev. Lett. 100, 065301 (2008)