Columbia subject headings:
Harvard subject headings:
Gays--Germany--North Rhine-Westphalia--Social conditions--Congresses.
Homosexuality--Germany--Emscher River (North Rhine-Westphalia)--History--20th century--Congresses.
Homosexuality--Germany--Emscher River (North Rhine-Westphalia)--History--21st century--Congresses.
Homosexuality--Germany--Ruhr (Region)--History--20th century--Congresses.
Homosexuality--Germany--Ruhr (Region)--History--21st century--Congresses.
Lesbians--Germany--North Rhine-Westphalia--Social conditions--Congresses.
Princeton subject headings:
Gays--Germany--North Rhine-Westphalia--Social conditions--Congresses.
Homosexuality--Germany--Emscher River (North Rhine-Westphalia)--History--20th century--Congresses.
Homosexuality--Germany--Emscher River (North Rhine-Westphalia)--History--21st century--Congresses.
Homosexuality--Germany--Ruhr (Region)--History--20th century--Congresses.
Homosexuality--Germany--Ruhr (Region)--History--21st century--Congresses.
Lesbians--Germany--North Rhine-Westphalia--Social conditions--Congresses.