PHYSICA C, vol. 185, page. 2063 - 2064, 1991-12-01
JOURNAL OF APPLIED PHYSICS, vol. 70, no. 10, page. 5661 - 5666, 1991-11-15
JOURNAL OF APPLIED PHYSICS, vol. 69, no. 9, page. 6716 - 6718, 1991-05-01
PHYSICAL REVIEW B, vol. 43, no. 4, page. 2962 - 2967, 1991-02-01