Plague of Justinian
Procopius. History of the Wars, Books I and II (The Persian War). Trans. H. B. Dewing. Vol. 1. Cambridge: Loeb-Harvard UP, 1954.—Chapters XXII and XXIII of Book II (pages 451–473) are Procopius's famous description of the Plague of Justinian. This includes the famous 10,000 people dead a day in Constantinople statistic (page 465).