Columbia subject headings:
Harvard subject headings:
Africa--Antiquities--Congresses.
Africa--Civilization--Congresses
Africa--Languages--Congresses.
Sociolinguistics--Africa--Congresses.
Princeton subject headings:
Africa--Antiquities--Congresses.
Africa--Civilization--Congresses.
Africa--Languages--Congresses.
Sociolinguistics--Africa--Congresses.