Columbia subject headings:
British--India--Kolkata--History.
Kolkata (India)--Commerce--History.
Merchants--India--Kolkata--History.
Harvard subject headings:
British--India--Kolkata--History.
Kolkata (India)--Commerce--History.
Merchants--India--Kolkata--History.
Princeton subject headings:
British--India--Calcutta--History.
Calcutta (India)--Commerce--History.
Merchants--India--Calcutta--History.