APA (7th ed.) Citation

Vollmer, A. (1921). Practical Method for Selecting Policemen.

Chicago Style (17th ed.) Citation

Vollmer, August. Practical Method for Selecting Policemen. 1921.

MLA (9th ed.) Citation

Vollmer, August. Practical Method for Selecting Policemen. 1921.

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