APA (7th ed.) Citation

Zilboorg, G. (1939). I won't apologize: Two letters. Privately Printed.

Chicago Style (17th ed.) Citation

Zilboorg, Gregory. I Won't Apologize: Two Letters. New York: Privately Printed, 1939.

MLA (8th ed.) Citation

Zilboorg, Gregory. I Won't Apologize: Two Letters. Privately Printed, 1939.