PREFIX  xsd:    <http://www.w3.org/2001/XMLSchema#>
PREFIX  dc:     <http://purl.org/dc/elements/1.1/>
PREFIX  :       <.>

SELECT *
FROM <ds-dft.ttl>
FROM NAMED <ds-ng-1.ttl>
FROM NAMED <ds-ng-2.ttl>
{ 
    { ?s ?p ?o } UNION { GRAPH ?g { ?s ?p ?o } } 
}