APA (7th ed.) Citation

Friedman, W. F. (1977). Solving German codes in World War I: With an added special "code problem" for the student. Aegean Park Press.

Chicago Style (17th ed.) Citation

Friedman, William F. Solving German Codes in World War I: With an Added Special "Code Problem" for the Student. Laguna Hills, California: Aegean Park Press, 1977.

MLA (9th ed.) Citation

Friedman, William F. Solving German Codes in World War I: With an Added Special "Code Problem" for the Student. Aegean Park Press, 1977.