APA (7th ed.) Citation

Levi, P. (1986). If not now, when? Penguin Books.

Chicago Style (17th ed.) Citation

Levi, Primo. If Not Now, When? New York, N.Y., U.S.A.: Penguin Books, 1986.

MLA (9th ed.) Citation

Levi, Primo. If Not Now, When? Penguin Books, 1986.