Question: Which writer of A literary Nightmare also extended the work of The Apple tree ?
SPARQL query: SELECT DISTINCT ?uri WHERE { <http://dbpedia.org/resource/The_Apple_Tree> <http://dbpedia.org/ontology/basedOn> ?uri. <http://dbpedia.org/resource/A_Literary_Nightmare> <http://dbpedia.org/ontology/author> ?uri}
Answer: The person where The Apple Tree was based and author of A Literary Nightmare is [Mark Twain].