Columbia subject headings:
Europe--Colonies--Administration--History--19th century.
Europeans--Drug use--Asia--History--19th century.
Opium trade--China--History--19th century.
Spain--Colonies--Administration--History--19th century.
Spain--Colonies--Race relations--History--19th century.
Harvard subject headings:
Colonization--History--19th century.
Europe--Colonies.
Imperialism--History--19th century
Princeton subject headings: