Columbia subject headings:
Language maintenance--Congresses.
Language purism--Congresses.
Sociolinguistics--Congresses.
Harvard subject headings:
Language maintenance--Congresses.
Language purism--Congresses.
Sociolinguistics--Congresses.
Princeton subject headings:
Language maintenance--Congresses.
Language purism--Congresses.
Sociolinguistics--Congresses.