JOURNAL OF THE KOREAN PHYSICAL SOCIETY, vol. 52, no. 4, page. 1206 - 1210, 2008-04
PHYSICAL REVIEW LETTERS, vol. 102, no. 24, page. 247603 - 247603, 2009-06-19
NATURE, vol. 449, no. 7164, page. 881 - 884, 2007-10-18
JOURNAL OF PHYSICS-CONDENSED MATTER, vol. 20, no. 1, 2008-01-09
, 2008-08