Library Eusebius of Caesarea Church History
Book 4
Chapter 4: The Bishops of Rome and of Alexandria under the Same Emperor
In the third year of the same reign, Alexander, bishop of Rome, died after holding office ten years. His successor was Xystus. About the same time Primus, bishop of Alexandria, died in the twelfth year of his episcopate, and was succeeded by Justus.
English translation by Arthur Cushman McGiffert, in Nicene and Post-Nicene Fathers, Series II, Vol. I (eds. Philip Schaff and Henry Wace; Buffalo: Christian Literature Publishing Co., 1890). Public domain. Digital text via New Advent Church Fathers.