Columbia subject headings:
Harvard subject headings:
China--Commerce--India.
China--Foreign relations--Great Britain.
Great Britain--Colonies--India.
Great Britain--Foreign relations--China.
India--Commerce--China.
Opium trade
Princeton subject headings:
China--Commerce--India.
China--Foreign relations--Great Britain.
Great Britain--Colonies--India.
Great Britain--Foreign relations--China.
India--Commerce--China.
Opium trade.