Mention the count of papers published by the authors of 'Query Modification in Object-Oriented Database Federations' in International Conference on Cooperative Information Systems.
How many papers did the authors of 'Query Modification in Object-Oriented Database Federations' publish in International Conference on Cooperative Information Systems?
SELECT DISTINCT (COUNT(?answer) AS ?count) WHERE { <https://dblp.org/rec/conf/coopis/VermeerA97> <https://dblp.org/rdf/schema#authoredBy> ?x . ?answer <https://dblp.org/rdf/schema#authoredBy> ?x . ?answer <https://dblp.org/rdf/schema#publishedIn> 'CoopIS' }
<https://dblp.org/rec/conf/coopis/VermeerA97>