In 1980 in International Conference on Conceptual Modelling, what are the titles of the papers on Relationship model?
In International Conference on Conceptual Modelling in 1980, what are the titles of the papers on Relationship model?
SELECT DISTINCT ?answer WHERE { <https://dblp.org/rec/conf/er/ChanL79> <https://dblp.org/rdf/schema#publishedIn> 'ER' . <https://dblp.org/rec/conf/er/ChanL79> <https://dblp.org/rdf/schema#yearOfPublication> '1980' . <https://dblp.org/rec/conf/er/ChanL79> <https://dblp.org/rdf/schema#title> ?answer }
<https://dblp.org/rec/conf/er/ChanL79>