In Robertson, Archibald T. “Introduction to Ad Episcopos Aegypti et Libyae Epistola Encyclica.” In St. Athanasius: Select Works and Letters, edited by Philip Schaff and Henry Wace, Vol. 4. A Select Library of the Nicene and Post-Nicene Fathers of the Christian Church, Second Series. New York: Christian Literature Company, 1892.
The introduction written by the editors is included in the letter itself. This is not the normal practice.
