Tomonobu Ozaki Takenao Ohkawa Efficient Mining of Closed Induced Ordered Subtrees in Tree-structured Databases. 279-283 2006 conf/icdm/2006w ICDM Workshops http://doi.ieeecomputersociety.org/10.1109/ICDMW.2006.67 db/conf/icdm/icdmw2006.html#OzakiO06