[1] Thucydides 2.7.1 and scholia, though the citations probably come most directly from Photius, Lexicon lambda78 Theodoridis (who has the whole of this opening part of the entry). The treaty in question, the Thirty Years Peace of 446/5 between the Greek alliances led by Athens and Sparta, was broken (by the Theban attack on Plataea) in 431. For Plataea see pi 1700; also epsilon 3954, xi 20.
[2] See e.g. (?)Aeschylus, Prometheus Bound 833. (And again in Thucydides: 8.67.3.)
[3] Procopius, History of the Wars of Justinian 2.5.1 (web address 1); cf. alpha 3035 and Kaldellis (81). The subject is the Sassanid Persian king Chosroes I (chi 418), who in 540 CE broke the “perpetual peace” by attacking the Byzantine emperor Justinian I. For further background on Chosroes's 540 invasion of the Roman east, see alpha 465 note.