Columbia subject headings:
Harvard subject headings:
Absence in literature--Congresses.
Nonexistent objects (Philosophy)--Congresses.
Semantics--Political aspects--Congresses.
Semantics--Social aspects--Congresses.
Semantics--Social aspects--France--Congresses.
Semantics--Social aspects--Germany--Congresses.
Princeton subject headings:
Absence in literature--Congresses.
Nonexistent objects (Philosophy)--Congresses.
Semantics--Political aspects--Congresses.
Semantics--Social aspects--Congresses.
Semantics--Social aspects--France--Congresses.
Semantics--Social aspects--Germany--Congresses.