Information Processing Letters
Information Processing Letters > 1998 > 65 > 5 > 235-240
Information Processing Letters > 1998 > 66 > 4 > 165-170
Information Processing Letters > 1999 > 71 > 3-4 > 97-105
Information Processing Letters > 2004 > 90 > 3 > 129-134
Information Processing Letters > 2008 > 105 > 6 > 218-223
Information Processing Letters > 2008 > 108 > 5 > 320-325