Columbia subject headings:
Opera--France--19th century--Congresses.
Harvard subject headings:
Eighteenth century in opera--Congresses.
Opera--18th century--Influence--Congresses.
Opera--France--19th century--Congresses.
Princeton subject headings:
Eighteenth century in opera--Congresses.
Opera--18th century--Influence--Congresses.
Opera--France--19th century--Congresses.