JOURNAL OF APPLIED PHYSICS, vol. 70, no. 10, page. 6166 - 6168, 1991-11-15
MATERIALS LETTERS, vol. 12, no. 4, page. 233 - 241, 1991-11
JOURNAL OF THE KOREAN PHYSICAL SOCIETY, vol. 24, no. 1, page. 51 - 54, 1991-01
PHYSICAL REVIEW B, vol. 41, no. 4, page. 2623 - 2626, 1990-02-01