APA (7th ed.) Citation

Marx, K., Engels, F., Mortier, J., & Badia, G. 1860-1861. Editions sociales (Paris).

Chicago Style (17th ed.) Citation

Marx, Karl, Friedrich Engels, Jean Mortier, and Gilbert Badia. 1860-1861. Editions sociales (Paris).

MLA (8th ed.) Citation

Marx, Karl, et al. 1860-1861. Editions sociales (Paris).