JOURNAL OF THE KOREAN PHYSICAL SOCIETY, vol. 26, page. S396 - S398, 1993-12
JOURNAL OF THE KOREAN PHYSICAL SOCIETY, vol. 26, page. S473 - S475, 1993-12
PHYSICAL REVIEW B, vol. 49, no. 23, page. 16248 - 16255, 1994-06-15
SOLID STATE COMMUNICATIONS, vol. 91, no. 5, page. 403 - 406, 1994-08
JOURNAL OF THE KOREAN PHYSICAL SOCIETY, vol. 28, page. S390 - S393, 1995-05