Columbia subject headings:
Europe--Politics and government--1848-1871.
Europe--Politics and government--1871-1918.
Tariff--Europe.
Harvard subject headings:
Europe--Politics and government--1848-1871.
Europe--Politics and government--1871-1918.
Tariff--Europe.
Princeton subject headings:
Europe--Politics and government--1848-1871.
Europe--Politics and government--1871-1918.
Tariff--Europe.