I did a small search on may 68 posters.
Here is a selection of what i found:
30 beautiful posters from the “Bibliothèque nationale de France”
29 of the most known posters (thumbnail size, unfortunately)
A dozen, medium resolution, Posters from the International Institute of Social History
Flickr page with 67, good quality, black&white posters
List with lots of low resolution pictures
Slideshow on YouTube
The book “500 affiches de Mai 68” by Vasco Gasquet (costs €19.00)
Here is a selection of what i found:
30 beautiful posters from the “Bibliothèque nationale de France”
29 of the most known posters (thumbnail size, unfortunately)
A dozen, medium resolution, Posters from the International Institute of Social History
Flickr page with 67, good quality, black&white posters
List with lots of low resolution pictures
Slideshow on YouTube
The book “500 affiches de Mai 68” by Vasco Gasquet (costs €19.00)