Tao Wang Huiyu Liu Haoxiang Xia Navigability of Hierarchical-Tag-Based Folksonomies. 289-297 2013 KSEM https://doi.org/10.1007/978-3-642-39787-5_24 conf/ksem/2013 db/conf/ksem/ksem2013.html#WangLX13