PREFIX data: <urn:x-local:>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
Prefix dc: <http://purl.org/dc/elements/1.1/>

SELECT ?name ?mbox ?date
LOAD   data:details
FROM   data:graph1  data:graph2
WHERE
    ( ?g dc:publisher ?name)
    ( ?g dc:date ?date )
    GRAPH ?g 
    {
      ( ?person foaf:name ?name )
      ( ?person foaf:mbox ?mbox )
    }