1. Annas, J., & Barnes, J. (2000). Sextus Empiricus: Outlines of Pyrrhonism. Cambridge University Press.
2. Austin, J. L. (1964). Sense and sensibilia. Oxford University Press.
3. Austin, J. L. (1979). Philosophical papers (3rd ed., pp. 117–133). Clarendon Press.
4. Barnes, J. (1998). The beliefs of a Pyrrhonists. In M. Burnyeat & M. Frede (Eds.), The original Sceptics (pp. 58–91). Hackett.
5. Barney, R. (1992). Appearances and impressions. Phronesis, 37(3), 283–313.