Institut mezhdunarodnogo rabochego dvizhenii︠a︡ (Akademii︠a︡ nauk SSSR), Mezhdunarodnai︠a︡ nauchnai︠a︡ konferentsii︠a︡ "Pi︠a︡tidesi︠a︡tiletie Okti︠a︡bri︠a︡ i mezhdunarodnyĭ rabochiĭ klass"