APA (7th ed.) Citation

Santayana, G. (1938). The realm of truth: Book third of Realms of being. C. Scribner's Sons.

Chicago Style (17th ed.) Citation

Santayana, George. The Realm of Truth: Book Third of Realms of Being. New York: C. Scribner's Sons, 1938.

MLA (9th ed.) Citation

Santayana, George. The Realm of Truth: Book Third of Realms of Being. C. Scribner's Sons, 1938.

Warning: These citations may not always be 100% accurate.