Columbia subject headings:
Germanic languages--Congresses.
Indo-European languages--Congresses.
Proto-Germanic language--Congresses.
Harvard subject headings:
Germanic languages--Congresses.
Indo-European languages--Congresses.
Proto-Germanic language--Congresses.
Princeton subject headings:
Germanic languages--Congresses.
Indo-European languages--Congresses.
Proto-Germanic language--Congresses.