DISCRETE MATHEMATICS, vol. 226, no. 1-3, page. 403 - 409, 2001-01-06
IEEE TRANSACTIONS ON INFORMATION THEORY, vol. 45, no. 4, page. 1255 - 1258, 1999-05
IEEE TRANSACTIONS ON INFORMATION THEORY, vol. 44, no. 1, page. 304 - 307, 1998-01