Socrates
Anonymous. Quoted in Gorgias, written by Plato. Oxford University Press, 2008. Originally a drinking song by an anonymous source.
Plato. Ἀπολογία Σωκράτους [Apology of Socrates]. Speech of legal self-defence which Socrates spoke at his trial for impiety and corruption. 399 BC, Athens, Greece.
Plato. "Apology." Plato: Euthyphro; Apology; Crito; Phaedo, translated by Christopher Emlyn-Jones and William Preddy. Harvard University Press, 2017.
Quoted in Theaetetus, by Plato
Socrates. Quoted in Θεαίτητος [Theaetetus], written by Plato. c. 369 BC.
Socrates. Quoted in Theaetetus, written by Plato, translated by John McDowell. Oxford University Press, 2014.
Socrates. Quoted in Φαίδων [Phaedo], written by Plato. c. 360 BC.
Socrates. Quoted in "Phaedo." Plato: Five Dialogues: Euthyphro, Apology, Crito, Meno, Phaedo, written by Plato, translated by G. M. A. Grube and John M. Cooper. Hackett Publishing, 2002.