Count the different affiliations of the authors of 'On properties of multicast routing trees'.
How many different affiliations do the authors of 'On properties of multicast routing trees' have?
SELECT (COUNT(DISTINCT ?answer) AS ?count) WHERE { <https://dblp.org/rec/journals/ijcomsys/JanicM06> <https://dblp.org/rdf/schema#authoredBy> ?x . ?x <https://dblp.org/rdf/schema#primaryAffiliation> ?answer }
<https://dblp.org/rec/journals/ijcomsys/JanicM06>