IEICE TRANSACTIONS ON COMMUNICATIONS, vol. E86B, no. 10, page. 2987 - 2995, 2003-10
ELECTRONICS LETTERS, vol. 39, no. 7, page. 634 - 635, 2003-04-03
IEICE TRANSACTIONS ON COMMUNICATIONS, vol. E86-B, no. 3, page. 1063 - 1072, 2003-03