Semantic Web
SPARQL 1.2 Query Language is a query language, and can be used for diverse data sources, contains capabilities for querying required and optional graph patterns along with their conjunctions and disjunctions. SPARQL also supports aggregation, subqueries, negation, creating values by expressions, extensible value testing, and constraining queries by source RDF graph. The results of SPARQL queries can be result sets or RDF graphs.
Virtuoso SPARQL Query Editor - BNE | Datos
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Virtuoso SPARQL Query Editor - Europeana
How to search for datasets in data.europa.eu
EDM EUROPEANA DATA MODEL