JOURNAL OF THE KOREAN PHYSICAL SOCIETY, vol. 51, no. 3, page. 912 - 915, 2007-09
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS, vol. 15, no. 5, page. 2518 - 2520, 1997-09
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS, vol. 13, no. 4, page. 2228 - 2232, 1995-07