APA (7th ed.) Citation

Retzlaff, F., Echterhoff, T., & Gundlach, W. (1925). Polizei-Handbuch. Retzlaff.

Chicago Style (17th ed.) Citation

Retzlaff, Friedrich, Theodor Echterhoff, and W. Gundlach. Polizei-Handbuch. Lübeck: Retzlaff, 1925.

MLA (8th ed.) Citation

Retzlaff, Friedrich, et al. Polizei-Handbuch. Retzlaff, 1925.