Modern Hagiography
Lives of the Saints by Alban Butler.
Lives of the Saints by Sabine Baring-Gould.
The Liturgical Year by Dom Guéranger.
Medieval Hagiography
Eusebius, Ecclesiastical History
Writings of Pope Linus
Art & Architecture
Warburg Institute Iconographic Institute
Medieval Religion Listserv – 2016 Dillon.
The Saints in Art by Joseph Maria von Radowitz.