PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX rel: <http://purl.org/vocab/relationship/>
SELECT DISTINCT ?name
WHERE
{ 
   ?doc foaf:maker ?author .
    { ?author foaf:knows [ foaf:name ?name] . }
    		UNION
    {?author rel:hasMet [ foaf:name ?name] . }
 }
ORDER BY DESC (?name)