Found

Art by Nicholas of Verdun, 12th century German engraver and goldsmith.

Photographs by German photographer Aura Hertwig.

NSA propaganda posters.

Landscapes by Huseyin Avni Lifij, Turkish Impressionist painter.

I should note that this piece, Zebras, is often considered the first piece of the movement.

Art by Victor Vasarely, a French-Hungarian artist often considered to be the grandfather of the Op Art movement.