Columbia subject headings:
Hungary--History--Uprising of 1848-1849.
Secret service--Austria.
Zerffi, G. G. (Gustavus George), 1820-1892.
Harvard subject headings:
Hungarians--Great Britain--Biography.
Hungary--History--Uprising of 1848-1849
Secret service--Austria--History.
Zerffi, G.G. (Gustavus George), 1820-1892.
Princeton subject headings: