The ninth edition of "Gardner's Art Through the Ages" (1991) contains over 1300 illustrations. This bibliography lists over 500 book and magazine sources with quality reproductions of the artworks illustrated in this edition.
"Special Bulletin #5: Source List for Illustrations in "Gardner's Art Through the Ages" (ninth edition),"
VRA Bulletin:Vol. 21:
1, Article 1.
Available at: https://online.vraweb.org/vrab/vol21/iss1/1