Ayer, A. J. (1956). The problem of knowledge. Penguin Books.
Chicago-čujuhus (17. p.)Ayer, A. J. The Problem of Knowledge. Harmondsworth, Middlesex: Penguin Books, 1956.
MLA-čujuhus (9. p.)Ayer, A. J. The Problem of Knowledge. Penguin Books, 1956.
Muitte dárkkistit čujuhemiid riektatvuođa, ovdal go geavahat daid iežat deavsttas.