Lives of the Saints by Alban Butler.
Lives of the Saints by Sabine Baring-Gould.
The Liturgical Year by Dom Guéranger.
Victories of the Martyrs by Saint Alphonsus Liguori.
An Alphabet of Saints by Robert Hugh Benson, Reginald Balfour, and Charles Ritchie.
Our Birthday Bouquet Culled from the Shrines of the Saints and the Gardens of the Poets by Eleanor C. Donnelly.
Pictorial Half Hours with the Saints by Auguste François Lecanu.
The Lives of Saints, with Other Feasts of the Year, According to the Roman Calendar by Peter Ribadeneira.
An excerpt from a homily by Saint Ambrose of Milan on Psalm 118 (scroll down to find).
Art & Architecture
The church of San Sebastiano fuori le mura in Rome
Three paintings by Andrea Mantegna, from over the course of his career from 1456 to 1490
A painting by Benozzo Gozzoli in the Collegiata in San Gimignano (1465)
A painting by Antonello da Messina (1476-1477)
A painting by Pietro Perugino (1490-1500)
A painting by El Greco in Palencia Cathedral (1576-1579)
And to learn more about the popularity of images of Saint Sebastian, but in Northern Europe, and his association with plague, read this open access scholarly article from the Journal of Historians of Netherlandish Art.
Sacred and Legendary Art volume II by Mrs. Jameson.
A Handbook of Christian Symbols and Stories of the Saints as Illustrated in Art by Clara Erskine Clement.
The Saints in Art with Their Attributes and Symbols, Alphabetically Arranged by Margaret E. Tabor.
Sacred Symbols in Art by Elizabeth Edwards Goldsmith.
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.