Cita APA (7a ed.)

Sobel, R. (1982). The challenge of freedom. Laidlaw.

Cita Chicago Style (17a ed.)

Sobel, Robert. The Challenge of Freedom. River Forest, Ill. [u.a.]: Laidlaw, 1982.

Cita MLA (9a ed.)

Sobel, Robert. The Challenge of Freedom. Laidlaw, 1982.