Columbia subject headings:
Grammar, Comparative and general--Number.
Indo-European languages--Grammar, Historical.
Indo-European languages--Number.
Harvard subject headings:
Grammar, Comparative and general--Number.
Indo-European languages--Grammar, Historical.
Indo-European languages--Number.
Princeton subject headings:
Grammar, Comparative and general--Number.
Indo-European languages--Grammar, Historical.
Indo-European languages--Number.