Greece
Euripides. Herakles' Children [Children of Heracles]. c. 430 BC, Athens, Greece.
Euripides. "The Children of Hercules." Euripides I: Alcestis; Medea; The Children of Heracles; Hippolytus, edited and translated by Mark Griffith, Glenn W. Most, David Grene, and Richmond Lattimore. University of Chicago Press, 2013.
Sophocles. Unnamed drama. 5th century BC, fragment 694.
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.
Aristophanes. Ὄρνιθες [Birds]. c. 414, Dionysia, Athens, Greece.
Aristophanes. "Birds." Aristophanes: The Complete Plays, translated by Paul Roche. New American Library/Berkley, 2005.
Thucydides. The History of the Peloponnesian War. c. 431 BC, bk. 5.
Thucydides. The Peloponnesian War, translated by Martin Hammond. Oxford University Press, 2009, bk. 5.
Plutarch. "Πῶς ἄν τις διακρίνοιε τὸν κόλακα τοῦ φίλου [How to Tell a Flatterer from a Friend]." Ἠθικά Ethika [Moralia]. c. 100 AD.
Plutarch. "How to Distinguish a Flatterer from a Friend." Essays. Penguin Classics, 1993.
Aeschylus. Agamemnon. 458 BCE, The Dionysia, Athens, Greece.
Aeschylus. "Agamemnon." The Oresteia: Agamemnon; The Libation Bearers; The Eumenides, edited and translated by Robert Fagles. Penguin Classics, 1984.
Quoted in Funeral Oration, by Thucydides
Pericles. Quoted in The History of the Peloponnesian War. c. 431 BC, bk. 2.
Pericles. Quoted in The Peloponnesian War, translated by Martin Hammond. Oxford University Press, 2009, bk. 2.
Epicurus. Quoted in Lives and Opinions of Eminent Philosophers, written by Diogenes Laertius. c. 240 AD, bk. 10, ch. 1, sect. 125.
Epicurus. Quoted in The Lives of Eminent Philosophers, written by Diogenes Laërtius, translated by Pamela Mensch, edited by James Miller. Oxford University Press, 2018, bk. 10, ch. 1, sect. 125.
Theognis. Elegies. c. 541 BC.
Theognis. "Elegies." Hesiod and Theognis: Theogony, Works and Days, and Elegies, translated by Dorothea Wender. Penguin Classics, 1976.
Plutarch. "Aemilius Paulus." Βίοι Παράλληλοι [Parallel Lives]. c. 2nd century.
Plutarch. "Aemilius." Roman Lives: A Selection of Eight Roman Lives, translated by Robin Waterfield. Oxford University Press, 2009.
Polybius. Ἱστορίαι [Histories]. c. 110 BC, bk. 10.
Polybius. The Histories, translated by W. R. Paton. Vol. 4, Loeb Classical Library, 1992, bk. 10.
Sophocles. "Hipponous." Fragments. c. 468 BC, frag. 301.
Sophocles. "Hipponous." Fragments, edited and translated by Hugh Lloyd-Jones. Harvard University Press, 1996, frag. 301.
Hippocrates. The Law. c. 4th century BC, pt. 4.
Hippocrates. "Canon." Hippocratic Writings, translated by J. Chadwick and W. N. Mann, et al. Penguin Classics, 1984.
Polybius. Ἱστορίαι [Histories]. c. 110 BC, bk. 18.
Polybius. The Histories, translated by W. R. Paton. Vol. 5, Harvard University Press, 2012, bk. 18.
Sophocles. Oedipus Rex. c. 429 BC, Theatre of Dionysus, Athens, Greece.
Sophocles. "Oedipus Rex." The Oedipus Cycle: Oedipus Rex; Oedipus at Colonus; Antigone, translated by Dudley Fitts and Robert Fitzgerald. Mariner Books, 2002.