Columbia subject headings:
Mainz (Rhineland-Palatinate, Germany)--Economic conditions--Congresses.
Mainz (Rhineland-Palatinate, Germany)--History--Congresses.
Harvard subject headings:
Mainz (Rhineland-Palatinate, Germany)--Economic conditions--Congresses.
Mainz (Rhineland-Palatinate, Germany)--History--Congresses.
Princeton subject headings:
Mainz (Rhineland-Palatinate, Germany)--Economic conditions--Congresses.
Mainz (Rhineland-Palatinate, Germany)--History--Congresses.