Question: From how many countries did the aeroplanes designed by Alexander Lippisch originate?
SPARQL query:
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX prop: <http://dbpedia.org/property/>
PREFIX onto: <http://dbpedia.org/ontology/>
SELECT DISTINCT COUNT(?uri) WHERE { ?x prop:designer <http://dbpedia.org/resource/Alexander_Lippisch> . ?x prop:nationalOrigin ?uri  . ?uri rdf:type onto:Country}