Guimei Liu Hongjun Lu Yabo Xu Jeffrey Xu Yu Ascending Frequency Ordered Prefix-tree: Efficient Mining of Frequent Patterns. 65-72 2003 conf/dasfaa/2003 DASFAA http://doi.ieeecomputersociety.org/10.1109/DASFAA.2003.1192369 db/conf/dasfaa/dasfaa2003.html#LiuLXY03