Juryon Paik Junghyun Nam Hee Yong Youn Ung-Mo Kim Discovery of Useful Patterns from Tree-Structured Documents with Label-Projected Database. 264-278 2008 ATC http://dx.doi.org/10.1007/978-3-540-69295-9_22 conf/atc/2008 db/conf/atc/atc2008.html#PaikNYK08