This list is selective, because my knowledge of the relevant secondary literature is limited, because it includes only things I think are valuable (though not necessarily correct), and because I have not listed articles within collections (e.g. Kraut's The Cambridge Companion to Plato) separately (the Syllabus will direct you to specific articles that can be found in books listed here).

• Adkins, A.  1960.  Merit and Responsibility (Clarendon).
• Annas, J. 1998. Platonic Ethics, Old and New (Cornell).
• 1981. An Introduction to Plato's Republic (Oxford).
• Barker, E. 1906. The Political Thought of Plato and Aristotle (Dover).
• Barnes, J. [ed.] 1987. Early Greek Philosophy (Penguin).
• Brink, D. 1999. "Eudaimonism, Love and Friendship, and Political Community" Social Philosophy & Policy 16.
• 1997. "Self-love and Altruism" Social Philosophy & Policy 14.
• Benson, H., ed. 1992. Essays on the Philosophy of Socrates (Oxford).
• Brickhouse, T. and Smith, N. 1989. Socrates on Trial (Princeton).
• Cooper, J. 1999. Reason and Emotion: Essays on Ancient Moral Psychology and Ethical Theory (Princeton).
• Cross, R. and Woozley, A. 1964. Plato's Republic (Macmillan).
• Devereux, D. 1992. "The Unity of the Virtues in Plato's Protagoras and Laches" Philosophical Review 101.
• Dover, K. 1974. Greek Popular Morality in the Time of Plato and Aristole (Blackwell).
• Fine, G.  2003. Plato on Knowledge and Forms (Clarendon).
• 1990. "Knowledge and Belief in Republic V-VIII" in Companions to Ancient Thought 1: Epistemology, ed. Everson (Cambridge) and in Fine 2003.
• 1984. "Separation" Oxford Studies in Ancient Philosophy 2 and in Fine 2003.
• 1982. "Aristotle and the More Accurate Arguments" in Language and Logos ed., Schofield and Nussbaum (Cambridge).
• 1980. "The One Over Many" Philosophical Review 89.
• [ed]. 2000. Plato: I and II (Clarendon).
• Gallop, D. 1975. Plato's Phaedo [trs. and notes] (Clarendon).
• Gosling, J. 1975. Plato's Philebus [trs. and notes] (Clarendon).
• 1973. Plato (Routledge).
• Gosling, J. and Taylor, C. 1982. The Greeks on Pleasure (Clarendon).
• Irwin, T. 1995. Plato's Ethics (Clarendon).
• 1989. "Socrates and Athenian Democracy" Philosophy & Public Affairs 18.
• 1986a. "Socratic Inquiry and Politics" Ethics.
• 1986b. "Objectivity and Coercion in Plato's Dialectic" Revue Internationale de Philosophie.
• 1986c. "Socrates the Epicurean" Illinois Classical Quarterly 11; reprinted in Benson 1992.
• 1979. Plato's Gorgias [trs. and notes] (Clarendon).
• 1977. Plato's Moral Theory (Clarendon).
• Kraut, R. 1984. Socrates and the State (Princeton).
• 1979. "Two Conceptions of Happiness" Philosophical Review 88.
• [ed]. 1992. The Cambridge Companion to Plato (Cambridge).
• McDowell, J. 1979. "Virtue and Reason" The Monist 62.
• Penner, T. 1973. "The Unity of Virtue" Philosophical Review 82.
• Popper, K. 1966. The Open Society and Its Enemies, vol. 1 (Princeton).
• Price, A. 1989. Love and Friendship in Plato and Aristotle (Clarendon).
• Reeve, C. 1988. Philosopher-Kings (Princeton).
• Rickless, S. 1998a. "How Parmenides Saved the Theory of Forms" Philosophical Review 107.
• 1998b. "Socrates' Moral Intellectualism" Pacific Philosophical Quarterly 79.
• Santas, G. 1979. Socrates (Routledge).
• Taylor, C. 1976. Plato's Protagoras [trs. and notes] (Clarendon).
• Vlastos, G. 1993. Socratic Studies (Cambridge).
• 1991. Socrates, Ironist and Moral Philosopher (Cornell).
• 1989. "Was Plato a Feminist?" Times Literary Supplement, March 17-23.
• 1981. Platonic Studies, 2d ed. (Princeton).
• 1971a. [ed]. Socrates (Notre Dame).
• 1971b. [ed]. Plato I (Notre Dame).
• 1971c. [ed]. Plato II (Notre Dame).
• 1956. Plato's Protagoras [trs. and intro] (Liberal Arts).
• White, N. 1986. "The Ruler's Choice" Archiv für Geschichte der Philosophie 68.
• 1985. "Rational Prudence in Plato's Gorgias" in Platonic Investigations, ed. O'Meara (Catholic University).
• 1984. "The Classification of Goods in Plato's Republic" Journal of the History of Philosophy 22.
• 1979. A Companion to Plato's Republic (Hackett).
• 1976. Plato on Knowledge and Reality (Hackett).