Columbia subject headings:
Harvard subject headings:
Airports--Germany--Information services.
Airports--Information services.
Public spaces--Germany--Information services.
Public spaces--Information services.
Railroads--Germany--Information services.
Railroads--Information services.
Signs and signboards--Social aspects--Germany.
Signs and signboards--Social aspects.
Visual communication--Social aspects--Germany.
Visual communication--Social aspects.
Princeton subject headings:
Airports--Germany--Information services.
Airports--Information services.
Public spaces--Germany--Information services.
Public spaces--Information services.
Railroads--Germany--Information services.
Railroads--Information services.
Signs and signboards--Social aspects--Germany.
Signs and signboards--Social aspects.
Visual communication--Social aspects--Germany.
Visual communication--Social aspects.