Modern Hagiography
Lives of the Saints by Alban Butler.
Lives of the Saints by Francis Weninger.
Lives of the Saints by Sabine Baring-Gould.
The Liturgical Year by Dom Guéranger.
Victories of the Martyrs by Saint Alphonsus Liguori.
Medieval Hagiography
The Golden Legend (and illustrations)
Art & Architecture
Warburg Institute Iconographic Database
Emblems of Saints by Which They Are Distinguished in Works of Art by F. C. Husenbeth.