APA (7th ed.) Citation

Engels, F., Sperl, R., & Westphal, F. (1967). Biographische Skizzen. Dietz.

Chicago Style (17th ed.) Citation

Engels, Friedrich, Richard Sperl, and Fred Westphal. Biographische Skizzen. Berlin: Dietz, 1967.

MLA (8th ed.) Citation

Engels, Friedrich, et al. Biographische Skizzen. Dietz, 1967.