PREFIX dc: <http://purl.org/dc/terms/>
PREFIX pgt: <http://www.gutenberg.org/2009/pgterms/>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
SELECT ?title ?subject ?author WHERE {
    ?book a pgt:ebook;
       dc:title ?title;
       dc:subject/rdf:value ?subject;
       dc:creator/pgt:name ?author .

}