How many research papers has Maria C. Pettenati published?
Mention the number of papers that Maria C. Pettenati has published.
SELECT (COUNT(DISTINCT ?answer) AS ?count) WHERE { ?answer <https://dblp.org/rdf/schema#authoredBy> <https://dblp.org/pid/57/864> }
<https://dblp.org/pid/57/864>