Columbia subject headings:
Kropotkin, Petr Alekseevich, kni︠a︡zʹ, 1842-1921.
Harvard subject headings:
Kropotkin, Petr Alekseevich, kni︠a︡zʹ, 1842-1921
Princeton subject headings:
Kropotkin, Petr Alekseevich, kni︠a︡zʹ, 1842-1921.