Columbia subject headings:
Harvard subject headings:
Police--Russia--History--19th century.
Russia--History--Nicholas I, 1825-1855.
Russia. Sobstvennai͡a Ego Imperatorskago Velichestva kant͡seli͡arīi͡a. III otdi͡elenīe.
Secret service--Russia--History--19th century.
Princeton subject headings:
Police--Russia--History--19th century.
Russia--History--Nicholas I, 1825-1855.
Russia. Sobstvennai︠a︡ Ego Imperatorskago Velichestva kant︠s︡eli︠a︡rīi︠a︡. III otdi︠e︡lenīe
Secret service--Russia--History--19th century.