Tillich, P., & Sardelli, G. (1964). The courage to be ([2nd impression].). Collins.
Cita Chicago Style (17a ed.)Tillich, Paul, y Giuseppe Sardelli. The Courage to Be. [2nd impression]. London [etc.]: Collins, 1964.
Cita MLA (9a ed.)Tillich, Paul, y Giuseppe Sardelli. The Courage to Be. [2nd impression]. Collins, 1964.
Precaución: Estas citas no son 100% exactas.