Columbia subject headings:
Intelligence service--Turkey--History--19th century.
Secret service--Turkey--History--19th century.
Turkey--History--Mahmud II, 1808-1839.
Turkey--History--Ottoman Empire, 1288-1918.
Harvard subject headings:
Intelligence service--Turkey--History--19th century.
Secret service--Turkey--History--19th century.
Turkey--History--Mahmud II, 1808-1839.
Turkey--History--Ottoman Empire, 1288-1918.
Princeton subject headings:
Intelligence service--Turkey--History--19th century.
Secret service--Turkey--History--19th century.
Turkey--History--Mahmud II, 1808-1839.
Turkey--History--Ottoman Empire, 1288-1918.