APA (7th ed.) Citation

Engels, F., & Marx, K. Revolution in Spain / by Karl Marx and Frederick Engels. London : Lawrence & Wishart, 1939.

Chicago Style (17th ed.) Citation

Engels, Friedrich, and Karl Marx. Revolution in Spain / by Karl Marx and Frederick Engels. London : Lawrence & Wishart, 1939.

MLA (8th ed.) Citation

Engels, Friedrich, and Karl Marx. Revolution in Spain / by Karl Marx and Frederick Engels. London : Lawrence & Wishart, 1939.

Warning: These citations may not always be 100% accurate.