PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> PREFIX sioc: <http://rdfs.org/sioc/ns#> PREFIX bibo: <http://purl.org/ontology/bibo/> SELECT * FROM <http://demo.openlinksw.com/Doc> WHERE { ?forum a sioc:Container . ?forum sioc:is_collection_of ?collection. OPTIONAL {?collection bibo:author ?author} . OPTIONAL {?collection bibo:identifier ?identifier} . OPTIONAL {?collection bibo:presentedAt ?presentedAt} . OPTIONAL {?collection bibo:url ?url} . OPTIONAL {?collection sioc:content ?content} . OPTIONAL {?collection sioc:description ?description} . } LIMIT 10