Columbia subject headings:
Iran--Commerce--Soviet Union--History--19th century--Sources.
Soviet Union--Commerce--Iran--History--19th century--Sources.
Harvard subject headings:
Iran--Commerce--Soviet Union--History--19th century--Sources.
Russia--Commerce--Iran--History--19th century--Sources.
Princeton subject headings:
Iran--Commerce--Russia--History--19th century--Sources.
Russia--Commerce--Iran--History--19th century--Sources.