Tomoyuki Kato Hajime Kitakami Makoto Takaki Keiichi Tamura Yasuma Mori Susumu Kuroki Extraction for Frequent Sequential Patterns with Minimum Varaible-Wildcard Regions. 825-831 2006 conf/pdpta/2006-2 PDPTA db/conf/pdpta/pdpta2006-2.html#KatoKTTMK06