File talk:0263.jpg
[http://www.nga.gov/content/ngaweb/research/casva/research-projects.html A Project of the National Gallery of Art, Center for Advanced Study in the Visual Arts ]
https://collection1.libraries.psu.edu/cdm/singleitem/collection/palmer/id/5411/rec/1
"This image is posted publicly for non-profit educational uses, excluding printed publication."
