PREFIX pubann:<http://pubannotation.org/ontology/>
SELECT ?s1 ?s2
WHERE {
  GRAPH prj:GlyCosmos600-GlycoEpitope {
    ?o1 tao:denoted_by ?s1 .
  }

  GRAPH prj:GlyCosmos600-MAT {
    ?o2 tao:denoted_by ?s2 .
  }

  ?s1 tao:belongs_to ?d1 .
  ?s2 tao:belongs_to ?d1 .
}