Columbia subject headings:
Harvard subject headings:
Igorʹ Svi͡atoslavich, novgorod-severskiĭ kni͡azʹ, 1151?-1202--Drama.
Operas--Librettos
Princeton subject headings:
Igorʹ Svi︠a︡toslavich, novgorod-severskiĭ kni︠a︡zʹ, 1151?-1202--Drama.
Librettos.
Operas--Librettos.