JOURNAL OF THE KOREAN PHYSICAL SOCIETY, vol. 51, no. 4, page. 1395 - 1399, 2007-10
NATURE PHYSICS, vol. 4, no. 3, page. 205 - 209, 2008-03
JOURNAL OF THE KOREAN PHYSICAL SOCIETY, vol. 49, page. 692 - 695, 2006-12
PHYSICAL REVIEW B, vol. 76, no. 3, page. 35316 - 35316, 2007-07