Diogenes Laertius: Life of Crates: From Lives of the Philosophers, translated by C.D. Yonge.
The Last Attachment: A Dialogue on War and the State: An imaginary dialogue between Crates and his student Zeno, by Jan Garrett.
Wikipedia: Crates of Thebes: Entry from this openly-edited encyclopedia, including information from the 1911 Britannica.