@electronic{heymann.stanford.edu, title = {Tag Hierarchies}, url = {http://heymann.stanford.edu/taghierarchy.html}, biburl = {https://puma.uni-kassel.de/url/87de09e3569428090272f60f719ead1b/hotho}, keywords = {hierarchy folksonomy ontology toread tag}, added-at = {2006-05-14T09:44:36.000+0200}, description = {}, interhash = {87de09e3569428090272f60f719ead1b}, intrahash = {87de09e3569428090272f60f719ead1b} }