JOURNAL OF ALGEBRA, vol. 124, no. 2, page. 284 - 299, 1989-08-01
JOURNAL OF ALGEBRA, vol. 123, no. 1, page. 151 - 170, 1989-05-15
JOURNAL OF ALGEBRA, vol. 122, no. 2, page. 323 - 336, 1989-05-01
COMMUNICATIONS IN ALGEBRA, vol. 17, no. 3, page. 553 - 564, 1989-01