PHYSICAL REVIEW B, vol. 72, no. 6, 2005-08
SOLID STATE COMMUNICATIONS, vol. 134, no. 4, page. 299 - 301, 2005-04
APPLIED PHYSICS LETTERS, vol. 86, no. 8, 2005-02-21
JOURNAL OF APPLIED PHYSICS, vol. 97, no. 4, 2005-02-15