Pro-library posters in the style of WWI and WWII.
I may have posted this link before, but it's a good one, so I don't mind repeating myself.
From the collection description:
What if the #savelibraries campaign had taken place between 1914-18? Then I expanded that out to World War 2 posters as well.
These are my two favorites, but there are loads more at flickr!
(Via Book Patrol)