Columbia subject headings:
Europe--Foreign relations--Soviet Union.
Revolutions--Europe.
Soviet Union--Foreign relations--Europe.
Soviet Union--History--Revolution, 1917-1921--Causes.
Harvard subject headings:
Europe--Foreign relations--Soviet Union.
Revolutions--Europe
Soviet Union--Foreign relations--Europe.
Soviet Union--History--Revolution, 1917-1921--Causes.
Princeton subject headings:
Europe--Foreign relations--Soviet Union.
Revolutions--Europe.
Soviet Union--Foreign relations--Europe.
Soviet Union--History--Revolution, 1917-1921--Causes.