How many {after a work by} are to/by {Jack London} ?
How many afterwords are by Jack London?
SELECT (COUNT(?sub) AS ?value ) { ?sub wdt:P1877 wd:Q45765 }
SELECT (COUNT(?sub) AS ?subs ) {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> ?sub .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P1877> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> http://wikidata.dbpedia.org/resource/Q45765 .
} 

How many afterwords did Jack London write?