Plato. Theaetetus. Translated by M.J.Levett, with an introduction by M.Burnyeat. Hackett 1990.
Aristotle. Nicomachean Ethics Book VI. Available online: http://classics.mit.edu/Aristotle/nicomachaen.6.vi.html
Aristotle. Posterior Analytics. Available online: http://classics.mit.edu/Aristotle/posterior.1.i.html