Library Eusebius of Caesarea Church History
Book 7
Chapter 4: The Epistles which Dionysius wrote on this Subject
Dionysius, therefore, having communicated with him extensively on this question by letter, finally showed him that since the persecution had abated, the churches everywhere had rejected the novelty of Novatus, and were at peace among themselves. He writes as follows:
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.