Ayer, A. J. (1956). The problem of knowledge. Penguin Books.
Chicago Style (17th ed.) ZitazioaAyer, A. J. The Problem of Knowledge. Harmondsworth, Middlesex: Penguin Books, 1956.
MLA (9th ed.) ZitazioaAyer, A. J. The Problem of Knowledge. Penguin Books, 1956.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.