@electronic{ontoworld.org,
   title       = {Semantic Web Topic Hierarchy - Ontoworld.org}, 
   url         = {http://ontoworld.org/wiki/Semantic_Web_Topic_Hierarchy},
   biburl      = {https://puma.uni-kassel.de/url/218e2c885bfedbdfc59aa9f6b3562397/hotho},
   keywords    = {hierarchy semantic topic web wiki},
   added-at    = {2007-09-07T10:38:34.000+0200},
   description = {},
   interhash   = {218e2c885bfedbdfc59aa9f6b3562397}, 
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}

@electronic{wiki.ontoworld.org,
   title       = {Semantic Web Topic Hierarchy - Ontoworld.org}, 
   url         = {http://wiki.ontoworld.org:80/index.php/Semantic_Web_Topic_Hierarchy},
   biburl      = {https://puma.uni-kassel.de/url/1ef705eb1e8a667f59d0cf1bbe4e2141/hotho},
   keywords    = {web 2.0 hierarchy topic wiki semantic},
   added-at    = {2006-12-06T14:45:53.000+0100},
   description = {Semantic Web Topic Hierarchy},
   interhash   = {1ef705eb1e8a667f59d0cf1bbe4e2141}, 
   intrahash   = {1ef705eb1e8a667f59d0cf1bbe4e2141}
}

@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}
}