https://www.visual-literacy.org/periodic_table/periodic_table.html
https://www.pinterest.com/pin/298222806561108420/?lp=true
https://www.tate.org.uk/art/artists/marcel-duchamp-1036
open culture: french revolution
http://www.openculture.com/2014/02/14000-free-images-from-the-french-revolution-now-available-online.html
