Plato, Ion,* Symposium, Phaedrus*
Recommended:
Kenney and Easterling, “Introduction to Plato on Poetry” in Plato and Poetry
Plato, Republic*
Gadamer, “Plato and the Poets”
Gonzalez, “The Hermeneutics of Madness: Poet and Philosopher in Plato’s Ion and Phaedrus” in Pierre Destrée and Fritz-Gregor Herrmann, eds., Plato and the Poets (full text here!)
Belfiore, “Poets at the Symposium,” alas not full text: here
Nehamas, “Plato and the Mass Media”
* This is the way classical internet archive access should work... Jowett, trans.