Columbia subject headings:
Congresses and conventions.
International relations--Congresses.
Language and languages--Political aspects.
Language, Universal.
Languages, Artificial.
Harvard subject headings:
Congresses and conventions
International relations--Congresses
Language and languages--Political aspects
Language, Universal.
Languages, Artificial.
Princeton subject headings:
Congresses and conventions.
International relations--Congresses.
Language and languages--Political aspects.
Language, Universal.
Languages, Artificial.