Columbia subject headings:
Socialism--Congresses.
Socialism--Russia.
Harvard subject headings:
Rossiĭskai︠a︡ sot︠s︡ial-demokraticheskai︠a︡ rabochai︠a︡ partii︠a︡--Congresses.
Rossiĭskai︠a︡ sot︠s︡ial-demokraticheskai︠a︡ rabochai︠a︡ partii︠a︡. Sʺezd (5th : 1907 : London, England)
Socialism--Congresses
Princeton subject headings:
Socialism--Congresses.
Socialism--Russia.