Columbia subject headings:
Communism--Soviet Union.
Partīi︠a︡ sot︠s︡īalistov-revoli︠u︡t︠s︡īonerov.
Soviet Union--History--Revolution, 1917-1921.
Harvard subject headings:
Partīi︠a︡ sot︠s︡īalistov-revoli︠u︡t︠s︡īonerov.
Soviet Union--History--Revolution, 1917-1921.
Princeton subject headings: