Question: Which American presidents were in office during the Vietnam War?
SPARQL query:
PREFIX res: <http://dbpedia.org/resource/> PREFIX onto: <http://dbpedia.org/ontology/> PREFIX dct: <http://purl.org/dc/terms/> PREFIX dbc: <http://dbpedia.org/resource/Category:> select distinct ?uri where { res:Vietnam_War onto:commander ?uri . ?uri dct:subject dbc:Presidents_of_the_United_States . }