Name the author who published the paper on Radio resource and has the name Stephen.
Which author named Stephen published the paper on Radio resource?
SELECT DISTINCT ?answer WHERE { <https://dblp.org/rec/conf/crowncom/AhmedHKPM09> <https://dblp.org/rdf/schema#authoredBy> ?answer }
<https://dblp.org/rec/conf/crowncom/AhmedHKPM09>