Petrus Christus, _Portrait of a Young Woman_ , c. 1470, oil on oak, 29 x 22.50 cm (Gemaldegalerie, Staatliche Museen zu Berlin). In the Google Art Project: http://www.googleartproject.com/collection/gemaldegalerie/artwork/portrait-of-a-young-woman-petrus-christus/324332/
License: CC BY-NC-SA by Khan Academy