DISCRETE MATHEMATICS, vol. 308, no. 18, page. 4057 - 4068, 2008-09-28
DISCRETE MATHEMATICS, vol. 288, no. 1-3, page. 37 - 47, 2004-11-28
DISCRETE MATHEMATICS, vol. 268, no. 1-3, page. 21 - 30, 2003-07-06