Find the number of authors of the paper 'Overview of the TREC-9 Web Track'.
How many authors does 'Overview of the TREC-9 Web Track' have?
SELECT ?answer WHERE { <https://dblp.org/rec/conf/trec/Hawking00> <https://dblp.org/rdf/schema#numberOfCreators> ?answer }
<https://dblp.org/rec/conf/trec/Hawking00>