Columbia subject headings:
Canals--Germany--Frankfurt am Main--History.
Frankfurt am Main (Germany)--History.
Public health--Germany--Frankfurt am Main--History.
Sanitary engineering--Germany--Frankfurt am Main--History.
Harvard subject headings:
Canals--Germany--Frankfurt am Main--History.
Frankfurt am Main (Germany)--History
Public health--Germany--Frankfurt am Main--History.
Sanitary engineering--Germany--Frankfurt am Main--History.
Princeton subject headings:
Canals--Germany--Frankfurt am Main--History.
Frankfurt am Main (Germany)--History.
Public health--Germany--Frankfurt am Main--History.
Sanitary engineering--Germany--Frankfurt am Main--History.