SKOS is a very common data model for representing knowledge in form of thesauri or controlled vocabularies which can provide for interlinked knowledge graphs as a form of linked data. SKOS is a lightweight and flexible OWL ontology representation format available in various RDF syntax. OWL on the other hand is an ontology language. It is possible to convert from SKOS to OWL and even to combine them. The below links provide some related tools and libraries for working with SKOS models.
JSKOS
SKOSAPI
OWLAPI
SKOSEd
OpenSKOS
TemTres
THManager
PoolParty
TopBraid
Thesaurus Master
Lexaurus
Fluent Editor
Intelligent Topic Manager
SKOS2OWL
Protege
SKOSIFY
Poolparty Consistency Checker
KEA
SKOSMOS
SILK
W3C SKOS
SKOS: A Guide for Information Professionals
SKOS Taxonomy
The Accidental Taxonomist
Knowledge Engineering with Semantic Web Technologies
LinkedData Engineering
PoolParty Academy
Gate
Ontotext
Knowledge Extraction
Taxonomy Warehouse
Synaptica
