@prefix skos:	<http://www.w3.org/2004/02/skos/core#> .
@prefix isac:	<http://webisa.webdatacommons.org/concept/> .
isac:_database_	skos:broader	isac:knowledge_source_ .
isac:_textbook_	skos:broader	isac:knowledge_source_ .
isac:_dictionary_	skos:broader	isac:knowledge_source_ .
isac:_teacher_	skos:broader	isac:knowledge_source_ .
isac:_internet_	skos:broader	isac:knowledge_source_ .
isac:_thesaurus_	skos:broader	isac:knowledge_source_ .
isac:_wikipedia_	skos:broader	isac:knowledge_source_ .