License, verbatimCC0
The Metropolitan Museum of Art: Open Access, Creative Commons Zero (CC0). Flagged isPublicDomain=true in the museum's own record.
Stefano della Bella. Plate 2: At top, the head of a young man, frontal view, at bottom, four eyes, from "The Book for Learning to Draw" (Livre pour apprendre à dessiner), ca. 1649. The Metropolitan Museum of Art.