Columbia subject headings:
Gay couples--Legal status, laws, etc.--Congresses.
Gay couples--Legal status, laws, etc.--Germany--Congresses.
Unmarried couples--Legal status, laws, etc.--Congresses.
Unmarried couples--Legal status, laws, etc.--Germany--Congresses.
Harvard subject headings:
Gay couples--Legal status, laws, etc.--Congresses.
Gay couples--Legal status, laws, etc.--Germany--Congresses.
Unmarried couples--Legal status, laws, etc.--Congresses.
Unmarried couples--Legal status, laws, etc.--Germany--Congresses.
Princeton subject headings: