Columbia subject headings:
Engels, Friedrich, 1820-1895.
Marx, Karl, 1818-1883.
Poland--History--19th century.
Socialism--Poland--History.
Harvard subject headings:
Engels, Friedrich, 1820-1895
Marx, Karl, 1818-1883
Poland--History--19th century
Poland--Politics and government--1796-1918
Revolutionaries--Poland--History.
Socialism--Poland
Socialism--Poland--History
Princeton subject headings:
Engels, Friedrich, 1820-1864.
Marx, Karl, 1818-1883.
Poland--History--19th century.
Socialism--Poland--History.