Cita APA (7th ed.)

Santayana, G., & Holzberger, W. G. (2003). The letters of George Santayana (Santayana ed.). MIT Press.

Cita Chicago (17th ed.)

Santayana, George, i William G. Holzberger. The Letters of George Santayana. Santayana ed. Cambridge, Mass.: MIT Press, 2003.

Cita MLA (9th ed.)

Santayana, George, i William G. Holzberger. The Letters of George Santayana. Santayana ed. MIT Press, 2003.