APA (7th ed.) Citation

Marx, K., Freedman, R., & Schwartz, H. (1971). Marx on economics. Penguin.

Chicago Style (17th ed.) Citation

Marx, Karl, Robert Freedman, and Harry Schwartz. Marx on Economics. Middlesex, England: Penguin, 1971.

MLA (9th ed.) Citation

Marx, Karl, et al. Marx on Economics. Penguin, 1971.