Columbia subject headings:
I͡Uzhnorossiĭskiĭ soi͡uz rabochikh.
Harvard subject headings:
I︠U︡zhnorossiĭskiĭ soi︠u︡z rabochikh.
Princeton subject headings:
I︠U︡zhnorossiĭskiĭ soi︠u︡z rabochikh.