NPNF2-01. Eusebius Pamphilius: Church History, Life of Constantine, Oration in Praise of Constantine

Chapter IV.—The Bishops of Rome and of Alexandria under the Same Emperor.⁹⁸⁹

In the third year of the same reign, Alexander,⁹⁹⁰ bishop of Rome, died after holding office ten years. His successor was Xystus.⁹⁹¹ About the same time Primus, bishop of Alexandria, died in the twelfth year of his episcopate,⁹⁹² and was succeeded by Justus.⁹⁹³