Pencil 4B on Canson.
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/40683483@N07">Arturo Espinosa</a> from barcelona, Cataluña (España)
CC BY 2.0
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/espinosa_rosique/8420987781/">Louis Althusser for Pifal</a>