Columbia subject headings:
Oral communication--History--To 1500--Congresses.
Voice--History--To 1500--Congresses.
Harvard subject headings:
Conference papers and proceedings
Oral communication--History--To 1500--Congresses.
Voice--History--To 1500--Congresses.
Princeton subject headings:
Oral communication--History--To 1500--Congresses.
Voice--History--To 1500--Congresses.