JOURNAL OF THE KOREAN PHYSICAL SOCIETY, vol. 53, no. 2, page. 986 - 989, 2008-08
SURFACE SCIENCE, vol. 602, no. 7, page. 1408 - 1412, 2008-04-01
PHYSICAL REVIEW B, vol. 61, no. 12, page. 8250 - 8255, 2000-03-15
PHYSICAL REVIEW LETTERS, vol. 84, no. 8, page. 1724 - 1727, 2000-02-21
PHYSICAL REVIEW B, vol. 61, no. 3, page. 1688 - 1691, 2000-01-15