query: SELECT ?item ?title ?retrieved WHERE {
    ?item wdt:P31 wd:Q3305213 .
    ?item p:P1476 ?titlestatement .
    ?titlestatement ps:P1476 ?title .
    ?titlestatement prov:wasDerivedFrom ?reference .
    ?reference pr:P143 wd:Q565 .
    OPTIONAL { ?reference pr:P813 ?retrieved } 
    } 