Drake, Maurice and Wilfred. Saints and Their Emblems. London: T. Werner Laurie, Ltd., 1971.
This is a good source that presents the saints in two different ways: The first part lists them by name and includes emblems and sources. The second part lists by attributes. It also includes a listing of the patriarchs and prophets along with their emblems and concludes with a listing of saints according to their role as patrons.
Jameson, Anna. Sacred and Legendary Art. 2 vols. London: Longmans, Green, & Co, 1883.
This older work continues to yield good information. In addition to giving the various attributes for the saints, she also gives the legends associated with them and then describes their representation in art. Vol. 1 covers the angels, apostles, Church Doctors, and major figures from the Bible. Vol. 2 covers the patron saints, the martyrs and the bishops. There is also a good index.
Roeder, Helen. Saints and Their Attributes. Chicago: Henry Regnery Co., 1956.
This is a good resource book, organized alphabetically, which lists both saints and attributes. It also includes a good bibliography.
Voragine, Jacobus de. The Golden Legend. Trans. Granger Ryan and Helmut Ripperger. New York: Longmans, Green and Co.,1948.
This is clearly the standard source on saints for the Middle Ages. It is organized according to the liturgical year and includes the stories and legends known and repeated in the Middle Ages.
Audsley, W. and G. Handbook of Christian Symbolism.
Clement, Clara Erskine. A Handbook of Christian Symbols and Stories of the Saints.
Ferguson, George. Signs and Symbols in Christian Art.
Hangen, Eva C. Symbols, Our Universal Langauge. Metford, J. C. J. Dictionary of Christian Lore and Legend.
Reau, Louis. Iconographie de L'Art Chretien.
Sill, Gertrude Grace. A Handbook of Symbols in Christian Art.