PHYSICAL REVIEW LETTERS, vol. 100, no. 3, page. 38103, 2008-01-25
PHYSICAL REVIEW B, vol. 75, no. 1, page. 12102, 2007-01
PHYSICAL REVIEW LETTERS, vol. 95, no. 8, page. 85503, 2005-08-19
PHYSICAL REVIEW LETTERS, vol. 97, no. 21, page. 215503, 2006-11-24