All the refseq elements from the Affimetrix database

Database: 
Statement: 

All the refseq elements from the Affimetrix database. Display a maximum of (e.g. 100) $number$ results.

Query: 
PREFIX void: <http://rdfs.org/ns/void#> PREFIX dv: <http://bio2rdf.org/bio2rdf.dataset_vocabulary:> SELECT ?identifier WHERE { ?x ?p <http://bio2rdf.org/refseq_vocabulary:Resource> . ?x <http://purl.org/dc/terms/identifier> ?identifier . } Limit ??number