Question: Who was the source of influence for the work of Edward Hopper.
Paraphrase: Who was the source of impact for the work of Edward Hopper.
SPARQL (Wikidata):  select distinct ?obj where { wd:Q203401 wdt:P737 ?obj . ?obj wdt:P31 wd:Q5 } 
Answer: Caspar David Friedrich, Gustave Caillebotte, Walter Sickert, Robert Henri, John Sloan