PROCEEDINGS OF THE AMERICAN MATHEMATICAL SOCIETY, vol. 126, no. 3, page. 645 - 646, 1998-03
JOURNAL OF ALGEBRA, vol. 200, no. 1, page. 347 - 362, 1998-02-01
COMMUNICATIONS IN ALGEBRA, vol. 26, no. 10, page. 3223 - 3238, 1998-01