PREFIX rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX dc:   <http://purl.org/dc/elements/1.1/>
PREFIX :     <http://example/ns#> 

SELECT ?book ?title 
WHERE
{ ?t rdf:subject    ?book  .
  ?t rdf:predicate  dc:title .
  ?t rdf:object     ?title .
  ?t :saidBy        "Bob" .
}