Columbia subject headings:
Communism--History--19th century.
Communists--Biography.
Engels, Friedrich, 1820-1895.
Marx, Karl, 1818-1883.
Harvard subject headings:
Communism--History--19th century
Communists--Biography
Engels, Friedrich, 1820-1895
Marx, Karl, 1818-1883
Princeton subject headings:
Communism--History--19th century.
Communists--Biography.
Engels, Friedrich, 1820-1895.
Marx, Karl, 1818-1883.