Library Eusebius of Caesarea Church History
Book 4, Chapter 20: The Rulers of the Church of Antioch.
1. At that time also in the church of Antioch, Theophilus was well known as the sixth from the apostles. For Cornelius, who succeeded Hero, was the fourth, and after him Eros, the fifth in order, had held the office of bishop.
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.