The original overview of Mortensen's work with a selection of images posted to the internet many times over. The first 1936 1st edition I have has amazing print quality on the photos. A most have book for Mortensen fan although American Grotesque is a better place to start for value and information.
It was decent, but I'd recommend "The Command to Look" over this one. This book was a little more technical and I didn't find it as relevant to today's photography.