Modern Mariology
The Liturgical Year by Dom Guéranger.
Our Birthday Bouquet Culled from the Shrines of the Saints and the Gardens of the Poets by Eleanor C. Donnelly.
Art & Architecture
Altarpiece of the Misericordia by Piero della Francesca
Madonna della Misericordia in the Capella Vespucci in the Church of Ognissanti by Domenico Ghirlandai
Warburg Institute Iconographic database
Wikipedia Entry on Our Lady of Mercy in art
Customs & Devotions
Nihil sub sole novum 