Columbia subject headings:
Harvard subject headings:
Grammar, Comparative and general--Verbals--Congresses.
Indo-European languages--Adjective--Congresses.
Indo-European languages--Grammar--Congresses.
Indo-European languages--Participle--Congresses.
Princeton subject headings:
Indo-European languages--Adjective--Congresses.
Indo-European languages--Congresses.
Indo-European languages--Participle--Congresses.