1. Resource Description Framework (RDF),
http://www.w3.org/RDF/
2. SPARQL 1.1 Query Language,
http://www.w3.org/TR/2010/WD-sparql11-query-20100601/
3. OWL 2 Web Ontology Language, Structural Specification and Functional-Style Syntax,
http://www.w3.org/TR/2009/REC-owl2-syntax-20091027/
4. RDF Vocabulary Description Language 1.0: RDF Schema,
http://www.w3.org/TR/rdf-schema/
5. Barrasa, J., Corcho, O., Shen, G., Gomez-Perez, A.: R2O: An extensible and semantically based database-to-ontology mapping language. In: SWDB 2004, 2nd Workshop on Semantic Web and Databases (2004)