JOURNAL OF APPLIED PHYSICS, vol. 76, no. 8, page. 4596 - 4602, 1994-10-15
JOURNAL OF APPLIED PHYSICS, vol. 73, no. 7, page. 3539 - 3542, 1993-04-01
JOURNAL OF NON-CRYSTALLINE SOLIDS, vol. 187, page. 149 - 155, 1995-07
JOURNAL OF APPLIED PHYSICS, vol. 72, no. 9, page. 4063 - 4072, 1992-11-01
APPLIED PHYSICS LETTERS, vol. 55, no. 17, page. 1768 - 1770, 1989-10-23