Columbia subject headings:
Communism.
Communist International. Congress (1st : 1919 : Moscow, Russia)
International.
Socialism.
Harvard subject headings:
Communism
Communist International
Communist International. Congress (1st : 1919 : Moscow, Russia)
Socialism
Princeton subject headings:
Communism.
Communist International (1st Congress : 1919 : Moscow, Russia)
International organization.
Socialism.