Hodie Octava est Natalis Domini cessate a superstitionibus idolorum.
Today is the octave of the day of the Lord: desist from the superstitions of idols!
Roman Martyrology.
Modern Hagiography
Lives of the Saints by Sabine Baring-Gould.
Deeds of Faith by John Mason Neale.
Medieval Hagiography
The Cult of Saints in Late Antiquity Database – Martyrologium Hieronymianum & Bede’s Martyrology
Theodoret’s Ecclesiastical History (pdf page 381 – html).
Art & Archaeology
Warburg Institute Iconographic Database
Nihil sub sole novum 