Rosalba Giugno Alfredo Pulvirenti Diego Reforgiato Recupero Clustered Trie Structures for Approximate Search in Hierarchical Objects Collections. 63-70 2005 conf/icapr/2005-1 ICAPR (1) http://dx.doi.org/10.1007/11551188_7 db/conf/icapr/icapr2005-1.html#GiugnoPR05