How many authors does the publication 'Blockchain for Education: Lifelong Learning Passport' have?
Find the number of authors of the paper 'Blockchain for Education: Lifelong Learning Passport'.
SELECT ?answer WHERE { <https://dblp.org/rec/journals/ercim/PrinzKR20> <https://dblp.org/rdf/schema#numberOfCreators> ?answer }
<https://dblp.org/rec/journals/ercim/PrinzKR20>