Cita APA (7th ed.)

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

Cita Chicago (17th ed.)

Ayer, A. J. The Problem of Knowledge. London ; Ringwood, Vic.: Penguin, 1956.

Cita MLA (8th ed.)

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