Cita APA (7th ed.)

Ayer, A. J. (1956). The problem of knowledge. Penguin Books.

Cita Chicago (17th ed.)

Ayer, A. J. The Problem of Knowledge. Harmondsworth, Middlesex: Penguin Books, 1956.

Cita MLA (9th ed.)

Ayer, A. J. The Problem of Knowledge. Penguin Books, 1956.