Modern Hagiography
Lives of the Saints by Sabine Baring-Gould.
Medieval Hagiography
The Golden Legend (and illustrations)
Art & Architecture
Warburg Institute Iconographic Database
Saints and their Symbols: A Companion in the Churches and Picture Galleries of Europe by E. A. Greene.
The Saints in Art by Joseph Maria von Radowitz.
Emblems of Saints by Which They Are Distinguished in Works of Art by F. C. Husenbeth.