Cita APA (7a ed.)

Santayana, G. (1972). Realms of being (One-volume ed.). Cooper Square.

Cita Chicago Style (17a ed.)

Santayana, George. Realms of Being. One-volume ed. New York: Cooper Square, 1972.

Cita MLA (9a ed.)

Santayana, George. Realms of Being. One-volume ed. Cooper Square, 1972.