Cita APA (7a ed.)

Tillich, P., & Sardelli, G. (1962). The courage to be. Collins.

Cita Chicago Style (17a ed.)

Tillich, Paul, y Giuseppe Sardelli. The Courage to Be. London [etc.]: Collins, 1962.

Cita MLA (9a ed.)

Tillich, Paul, y Giuseppe Sardelli. The Courage to Be. Collins, 1962.