Mention the year in which University of British Columbia published a paper on Spectrum watermarking.
When was the research paper on Spectrum watermarking by University of British Columbia, Vancouver, Canada published?
SELECT DISTINCT ?answer WHERE { <https://dblp.org/rec/conf/icip/NezhadaryaWW09> <https://dblp.org/rdf/schema#authoredBy> ?x . ?x <https://dblp.org/rdf/schema#primaryAffiliation> 'University of British Columbia, Vancouver, Canada' . <https://dblp.org/rec/conf/icip/NezhadaryaWW09> <https://dblp.org/rdf/schema#yearOfPublication> ?answer }
<https://dblp.org/rec/conf/icip/NezhadaryaWW09>