The Civil War in the United States /
by Karl Marx and Frederick Engels.

APA Citation

Marx, K., Engels, F. (1961). The Civil War in the United States. [3d ed.]. New York: International Publishers.

MLA Citation

Marx, Karl, 1818-1883, and Friedrich Engels. The Civil War In the United States. [3d ed.]. New York: International Publishers, 1961.

Warning: These citations may not always be complete (especially for serials).